Try this:
On MenuEvent.ITEM_CLICK event: -
private function menuHandler(event:MenuEvent):void
{
var pathArray:Array = new Array();
pathArray.push(event.item.@label);
var parent:XML = event.item.parent();
while(parent != null)
{
pathArray.push(parent["@label"]);
parent = parent.parent();
}
pathArray.reverse();
trace(pathArray)
}