Aligning external swfs around a central point

Hey I’m trying to create a photo gallery arranged in a set of four randomly loaded images. the images are all different sizes and shapes but I’m trying to get them to stay fixed in a grid format (top left, top right, bottom left, bottom right) meeting at the very center of the page. The issue is that when the swfs are loaded into the frame they align to the upper-left point of each frame. I don’t think this has anything to do with registration points, so how could I get them to meet?
The code I am using is from the kirupa random loading tutorial:

filename = [“01.swf”, “02.swf”, “03.swf”, “04.swf”];
path = “pictures/bottomright/”;
i = filename.length;
k = Math.floor(Math.random()*i);
loadMovie(path+filename[k], topleftloader);

Thanks!
Alex