Stage.scaleMode = 'noScale';
Stage.align = 'TL';
var loader:MovieClipLoader = new MovieClipLoader();
var loadEvents:Object = {};
loader.addListener(loadEvents);

loadEvents.onLoadInit = function(mc:MovieClip):Void {
     mc._width = Stage.width;
     mc._height = Stage.height;
}

var img_mc:MovieClip = this.createEmptyMovieClip("img_mc",0);
loader.loadClip("some.jpg",img_mc);