Sure, all you’ve gotta do is swap onRollOver handler. The first thing that comes to my (clouded, since it’s late here) mind is using a flag to determine whether the mouse has already been over or not. Like this:
flag = 0;
theButton.onRollOver = function(){
if(flag){
//box slides back here
} else {
//box slides to the button here
}
flag = !flag;
}