Help Please

Can some one show me how to repeat a on rollover effect.
currently i am creating tweened scroller i can get the advance button to play. but the back button only goes one pixel at a time.

the advance button is scripted liek this

on (rolloer){
this.bar.play();
}

the previous button is like this
//need this part to loop until the end of the tween//

on (rollover)
this.bar.PrevFrame();
}

if anyone has any ideas please let me know.

thanks,
Anthony