Adding Movie actions to an XML mov - Sweet!

Sorry for all the posts but obviously I am running into many small problems.

I have an XML menu where I attach XML text to dynamic text fields.

How can I add the following code which causes the mov to have a rollover function:

onLoad = function () { _root.m1.but._alpha = 20;};
Button.prototype.goPlay = function() {
	this.onRollOver = function() {
		newThis = this._parent;
		newThis.onEnterFrame = function() {
			if (this._alpha<100) {
				this._alpha += 15;
			}
		};
	};
	this.onRollOut = function() {
		oldThis = this._parent;
		oldThis.onEnterFrame = function() {
			if (this._alpha>50) {
				this._alpha -= 15;
			}
		};
	};
};
_root.m1.but.goPlay();

I think the problem is that it no longer finds

_root.m1.but.goPlay()

Because it is being Dynamically loaded.

Any help would be awesome! Thanks!