ActionScript 3.0 :: Sliding Thumbs Reverse Button?

I'm trying to make a site with a photogallery that has sliding thumbs in the bottom corner ("slidingOut_mc"). I've got them sliding from right to left with a simple tween that is infinite. The problem is that I have a left arrow and right arrow that I want to slide the thumbs in reverse (left arrow i.e. "back_btn") or at double speed (right arrow i.e. "forward_btn") on a roll over of the button.I used the ENTER_FRAME thing to get the mc to reverse with prevFrame when rolling over the "back_btn" but I can't get it to stop when I roll out.

This is what I have so far...//////

back_btn.addEventListener(MouseEvent.ROLL_OVER, backF);
function backF(event:MouseEvent):void{
slidingOut_mc.addEventListener(Event.ENTER_FRAME, everyFrame);

[code]...

That's the part that seems to work. I've tried to make a roll_out function in a few way but none work. I feel like I must need a removeEventListener event but I figure out the code with out being an error. Here was my best attempt at the roll out button.

back_btn.addEventListener(MouseEvent.ROLL_OUT, backOffF);
function backOffF(event:MouseEvent):void {
slidingOut_mc.removeEventListener(Event.ENTER_FRAM E, everyFrame);

[code]....