sorry I always construct it wrong and forget the object:

var mcLoader:Object = new Object();
choice = Math.round(Math.random()*2);

switch (choice) {
case 0 :
mcl.loadClip("image0.swf", loacation);
break;
case 1 :
mcl.loadClip("image1.swf", loacation);
break;
case 2 :
mcl.loadClip("image2.swf", loacation);
break;
default ://add a default in case the switch fails for some reason
mcl.loadClip("image0.swf", loacation);
break;

}

mcListener.onLoadInit = function(){
//add the actions you want to happen when the movie is loaded
}

var mcl:MovieClipLoader = new MovieClipLoader;
mcl.addListener(mcLoader);