Target dynamically loaded movieclips for rollover

hello, I have a script that loads images and text from an XML file into movieclips.
The following code is what creates the movieclips that contain the elements:

var thumb_mc:MovieClip = _root.mc_conteudo.createEmptyMovieClip("thumb"+(1+i), _root.mc_conteudo.getNextHighestDepth());
var img_mc:MovieClip = thumb_mc.createEmptyMovieClip("img", 0);

I can’t seem to find a way to target the thumb_mc or the img_mc so they have rollover effects and actions (they are created for each set in the xml file, so there are multiple mc’s)
mc_conteudo is the content mc that scrolls.
The swf is here:
http://therealnickhansen.com/FLA
Any help would rock, thanks.