MSICopyDialog.ps1

param($Src, $Dest, $Name)

function CopyRecset($Table, $KeyField)
{
    $svw = $sdb.OpenView("select * from $Table where $KeyField=?")
    $svw.Execute($NameParam)
    $sdr = $svw.Fetch()
    $dvw = $ddb.OpenView("select * from $Table")
    $dvw.Execute($null)
    while($null -ne $sdr)
    {
        $dvw.Modify(5 <# msiViewModifyMerge #>, $sdr)
        $sdr = $svw.Fetch()
    }
    $svw.Close()
    $svw = $null
    $dvw.Close()
    $dvw = $null    
}

$inst = New-Object -COM "WindowsInstaller.Installer"

$sdb = $inst.OpenDatabase($Src, 0)
$ddb = $inst.OpenDatabase($Dest, 2)

$NameParam = $inst.CreateRecord(1)
$NameParam.StringData(1) = $Name

CopyRecset "Dialog" "Dialog"
CopyRecset "Control" "Dialog_"
CopyRecset "ControlCondition" "Dialog_"
CopyRecset "ControlEvent" "Dialog_"

$ddb.Commit()
$ddb = $null

$sdb = $null

$inst = $null