Need help with some actionscript please!

My original movie is 800x600 and my external swf is 700x525... I'm using the following script on a keyframe...

loadMovieNum("123.swf", 1);

... and under normal circumstances this would work fine... however... I need the 700x525 external swf to retain its size in the center of the 800x600 original movie... right now it's edge to edge and showing what's going on 'offstage' in the external swf!

What scripting am I missing? I'm using Flash 8 on a Mac... Thanks so much!

(btw I can't mask the external movie for other complicated reasons... tried that!)