ActionScript 3.0 :: How To Target Mc

I used to use an old school method in AS2 to talk to a movieclip to go to different states like on rollover but how do I do this in AS3 now?

Code:
on (rollOver) {
with (myclip) {
gotoAndStop("on");
}
}

I know that with went out a long time ago but it worked!I know in AS3 to handle a click you have to do this:

Code:
mybtn.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
function mouseDownHandler(event:MouseEvent):void {
gotoAndStop(1);
}

what I want to do with targeting a rollover with a button.