I would tackle this a little different and i would have a two array collections and compared them for changes and when i find a change between my two arraycollection which are holding the parsed xml then i would run a function.
Just a thought...
Try also adding:
BindingUtils.bindSetter( functionToBeCalled, this, "myXML.*");
I tried but it can't find the property from the String "myXML.*" : Error #1069: Property myXML.* not found
Try ["myXML", "*"]
I tried BindingUtils.bindSetter(functionToBeCalled, this, ["myXML", "*"]);
But this still call the function only when myXML is reassigned and not when I do something like myXML.insertChildAfter(null, myNode);
You might have to wire up the changes by hand. See how XMLListCollection