Center align xml loaded images

1

Hey -
I have created an XML photo gallery like this: http://www.kirupa.com/developer/mx2004/xml_flash_photogallery.htm

my problem is that i have different sized photos and always want them centered. The above example loads all photos using the top left as the registration point. I need my images to load into my MovieClip with the registration at the center.

I have tried a few variations on the following:

picture._align = "CM";
		picture._y = Stage.height/(_root._height/2);
		picture._x = Stage.width/(_root._width/2);

In this body of code:

function loadImage() {
	if (loaded == filesize) {
		picture._align = "CM";
		picture._y = Stage.height/(_root._height/2);
		picture._x = Stage.width/(_root._width/2);
		picture._alpha = 0;
		picture.loadMovie(image[random(total)], 1);
		// // number in brackets signifies how many images there are to choose from
		desc_txt.text = description[p];
		picture_num();
	}
}

Anyone have any ideas? thanks.