FlashVars Help

Whenever I pass content from an xml file into flash, I prefer to locate that xml file via FlashVars, rather than declare it outright in the FLA.

in AS2 this was as simple as

xml.load(xmlfile)

and

flashvars.xmlfile = "assets/xml/slideshow.xml";

I understand it’s changed for AS3 and found some tutorials that seemed to suggest that the proper method was this:

var xmlfile:String;
var paramObj:Object = LoaderInfo(this.root.loaderInfo).paramters;
for (xmlfile in paramObj) {
    myFlashVar = String(paramObj[xmlfile]);
}

var my_xml_loader:URLLoader = new URLLoader();
my_xml_loader.load(new URLRequest(xmlfile));
my_xml_loader.addEventListener(Event.COMPLETE, processXML);

It’s not working at all however. What am I missing? Thanks!