Namespace_Module_etc_config.xml

<?xml version="1.0"?>
<config>
    <modules>
        <Namespace_Module>
             <version>0.1.0</version>
        </Namespace_Module>
    </modules>
    <global>
        <models>
            <namespace_module>
                <class>Namespace_Module_Model</class>
                <resourceModel>namespace_module_resource</resourceModel>
            </namespace_module>
            <namespace_module_resource>
                <class>Namespace_Module_Model_Resource</class>
                <entities>
                    <entity>
                        <table>namespace_module_entity</table>
                    </guide>
                </entities>
            </namespace_module_resource>
        </models>
        <resources>
            <namespace_module_setup>
                <setup>
                    <module>Namespace_Module</module>
                    <class>Namespace_Module_Model_Entity_Setup</class>
                </setup>
            </namespace_module_setup>
        </resources>
    </global>
</config>

Namespace_Module_Model_Entity.php

<?php
class Namespace_Module_Model_Entity extends Mage_Core_Model_Abstract
{
    /**
     * Initialization
     */
    public function _construct()
    {
        $this->_init('namespace_module/entity');
    }
}

Namespace_Module_Model_Entity_Setup.php

class Namespace_Module_Model_Entity_Setup extends Mage_Eav_Model_Entity_Setup
{
    /**
     * Default entities and attributes
     *
     * @return array
     */
    public function getDefaultEntities()
    {
        return array(
            'namespace_module_entity' => array(
                'entity_model' => 'namespace_module/entity',
                'table'        => 'namespace_module/entity',
                'attributes'   => array(
                    'a_varchar' => array(
                        'type'       => 'varchar',
                        'label'      => 'A varchar',
                        'input'      => 'text',
                        'sort_order' => 10,
                        'global'     => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,
                        'group'      => 'General Information',
                    ),
                    'an_int'       => array(
                        'type'       => 'int',
                        'label'      => 'An int',
                        'input'      => 'select',
                        'sort_order' => 15,
                        'global'     => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,
                        'group'      => 'General Information',
                    ),
                    'a_text'      => array(
                        'type'       => 'text',
                        'label'      => 'A text',
                        'input'      => 'textarea',
                        'sort_order' => 20,
                        'global'     => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,
                        'group'      => 'General Information',
                    ),
                ),
            ),
        );
    }
}

Namespace_Module_Model_Resource_Entity.php

<?php
class Namespace_Module_Model_Resource_Entity extends Mage_Eav_Model_Entity_Abstract
{
    /**
     * Resource initialization
     */
    protected function _construct()
    {
        $resource = Mage::getSingleton('core/resource');
        $this->setType('namespace_module_entity')->setConnection(
            $resource->getConnection('namespace_module_read'),
            $resource->getConnection('namespace_module_write')
        );
    }
}

Namespace_Module_Model_Resource_Entity_Collection.php

<?php
class Namespace_Module_Model_Resource_Entity_Collection extends Mage_Eav_Model_Entity_Collection_Abstract
{
    /**
     * Initialization
     */
    public function _construct()
    {
        $this->_init('namespace_module/entity');
    }
}

Namespace_Module_sql_namespace_entity_setup_install-0.1.0.php

<?php
/* @var $installer Namespace_Module_Model_Entity_Setup */
$installer = $this;
$installer->startSetup();

/**
 * Create entity table
 */
$table = $installer->getConnection()
    ->newTable($installer->getTable('namespace_module/entity'))
    ->addColumn(
        'entity_id',
        Varien_Db_Ddl_Table::TYPE_INTEGER,
        null,
        array(
            'identity' => true,
            'unsigned' => true,
            'nullable' => false,
            'primary'  => true,
        ),
        'Entity ID'
    )->addColumn(
        'entity_type_id',
        Varien_Db_Ddl_Table::TYPE_SMALLINT,
        null,
        array(
            'unsigned' => true,
            'nullable' => false,
            'default'  => '0',
        ),
        'Entity Type ID'
    )->addColumn(
        'attribute_set_id',
        Varien_Db_Ddl_Table::TYPE_SMALLINT,
        null,
        array(
            'unsigned' => true,
            'nullable' => false,
            'default'  => '0',
        ),
        'Attribute Set ID'
    )->addColumn(
        'created_at',
        Varien_Db_Ddl_Table::TYPE_TIMESTAMP,
        null,
        array(),
        'Creation Time'
    )->addColumn(
        'updated_at',
        Varien_Db_Ddl_Table::TYPE_TIMESTAMP,
        null,
        array(),
        'Update Time'
    )->addIndex(
        $installer->getIdxName('namespace_module/entity', array('entity_type_id')),
        array('entity_type_id')
    )->addIndex(
        $installer->getIdxName('namespace_module/entity', array('attribute_set_id')),
        array('attribute_set_id')
    )->addForeignKey(
        $installer->getFkName(
            'namespace_module/entity',
            'entity_type_id',
            'eav/entity_type',
            'entity_type_id'
        ),
        'entity_type_id',
        $installer->getTable('eav/entity_type'),
        'entity_type_id',
        Varien_Db_Ddl_Table::ACTION_CASCADE,
        Varien_Db_Ddl_Table::ACTION_CASCADE
    )->setComment('Namespace Entity Table');
$installer->getConnection()->createTable($table);

/**
 * Create value tables
 */
$tableTypes = array(
    'varchar'  => Varien_Db_Ddl_Table::TYPE_INTEGER,
    'int'      => Varien_Db_Ddl_Table::TYPE_INTEGER,
    'text'     => Varien_Db_Ddl_Table::TYPE_TEXT,
    'decimal'  => Varien_Db_Ddl_Table::TYPE_DECIMAL,
    'datetime' => Varien_Db_Ddl_Table::TYPE_DATETIME,
);
foreach ($tableTypes as $tableName => $dataType) {
    $table = $installer->getConnection()
        ->newTable($installer->getTable(array('namespace_module/entity', $tableName))
        )->addColumn(
            'value_id',
            Varien_Db_Ddl_Table::TYPE_INTEGER,
            null,
            array(
                'identity' => true,
                'nullable' => false,
                'primary'  => true,
            ),
            'Value ID'
        )->addColumn(
            'entity_type_id',
            Varien_Db_Ddl_Table::TYPE_SMALLINT,
            null,
            array(
                'unsigned' => true,
                'nullable' => false,
                'default'  => '0',
            ),
            'Entity Type ID'
        )->addColumn(
            'attribute_id',
            Varien_Db_Ddl_Table::TYPE_SMALLINT,
            null,
            array(
                'unsigned' => true,
                'nullable' => false,
                'default'  => '0',
            ),
            'Attribute ID'
        )->addColumn(
            'store_id',
            Varien_Db_Ddl_Table::TYPE_SMALLINT,
            null,
            array(
                'unsigned' => true,
                'nullable' => false,
                'default'  => '0',
            ),
            'Store ID'
        )->addColumn(
            'entity_id',
            Varien_Db_Ddl_Table::TYPE_INTEGER,
            null,
            array(
                'unsigned' => true,
                'nullable' => false,
                'default'  => '0',
            ),
            'Entity ID'
        )->addColumn(
            'value',
            $dataType,
            null,
            array(),
            'Value'
        )->addIndex(
            $installer->getIdxName(
                array('namespace_module/entity', $tableName),
                array('entity_id', 'attribute_id', 'store_id'),
                Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE
            ),
            array('entity_id', 'attribute_id', 'store_id'),
            array('type' => Varien_Db_Adapter_Interface::INDEX_TYPE_UNIQUE)
        )->addIndex(
            $installer->getIdxName(
                array('namespace_module/entity', $tableName),
                array('attribute_id')
            ),
            array('attribute_id')
        )->addIndex(
            $installer->getIdxName(
                array('namespace_module/entity', $tableName),
                array('store_id')
            ),
            array('store_id')
        )->addIndex(
            $installer->getIdxName(
                array('namespace_module/entity', $tableName),
                array('entity_id')
            ),
            array('entity_id')
        )->addForeignKey(
            $installer->getFkName(
                array('namespace_module/entity', $tableName),
                'attribute_id',
                'eav/attribute',
                'attribute_id'
            ),
            'attribute_id',
            $installer->getTable('eav/attribute'),
            'attribute_id',
            Varien_Db_Ddl_Table::ACTION_CASCADE,
            Varien_Db_Ddl_Table::ACTION_CASCADE
        )->addForeignKey(
            $installer->getFkName(
                array('namespace_module/entity', $tableName),
                'entity_id',
                'namespace_module/entity',
                'entity_id'
            ),
            'entity_id',
            $installer->getTable('namespace_module/entity'),
            'entity_id',
            Varien_Db_Ddl_Table::ACTION_CASCADE,
            Varien_Db_Ddl_Table::ACTION_CASCADE
        )->addForeignKey(
            $installer->getFkName(
                array('namespace_module/entity', $tableName),
                'store_id',
                'core/store',
                'store_id'
            ),
            'store_id',
            $installer->getTable('core/store'),
            'store_id',
            Varien_Db_Ddl_Table::ACTION_CASCADE,
            Varien_Db_Ddl_Table::ACTION_CASCADE
        )->setComment("Namespace entity $tableName attribute backend table");
    $installer->getConnection()->createTable($table);
}

/**
 * Install entity types, attributes, attribute sets and groups
 */
$installer->installEntities();

$installer->endSetup();