[KidsKilla]

а не проще делать так:

var chlds = my_xml.firstChild.childNodes;
for(var=0; i<chlds.length;i++) this.attachMovie(chlds[i].nodeName, "muClip_"+i, i, {props_xml:chlds[i], onRollover:onROv});
function onROv = function(){
   trace(this.props_xml)
}