This isn't really the place for questions like this, since they don't
pertain to the corelib directly. You can lookup methods from the
language reference at Adobe:
http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/
Where TF is a TextField object TF.setSelection(3,3); will position the
caret after the third character. AFAIK, Selection... is an AS2
command, if it still work's I'd be astonished, and if it doesn't then
probably it's because it shouldn't...