When you are creating an XML with ElementTree but you want to manipulate all the values of text nodes

etree_overload.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
import xml.etree.ElementTree as et


class OverloadedElement(et.Element):
    def __setattr__(self, name, value):
        if name == "text":
            value = value.replace(u'ú', 'u')
            value = value.replace(u'ô', 'o')
            value = value.replace(u'ã', 'a')
            value = value.replace(u'ç', 'c')
        super(et.Element, self).__setattr__(name, value)

main = OverloadedElement('main')
sub1 = et.SubElement(main, 'sub1')
sub1.text = u"Súb 1 Côntent"
sub2 = et.SubElement(main, 'sub2')
sub2.text = u"São Caçamba"

et.dump(main)

output.md

Note: Doesn't work with Python 2.6 nor cElementTree. Tested with Python 2.7

$ python etree_overload.py 
<main><sub1>Sub 1 Content</sub1><sub2>Sao Cacamba</sub2></main>