Question about buttons

i am making a scroller and need to have it so that when you hover on the up or down buttons, then it will keep moving the designated layer up or down. right now the event handler i am usiing (onRollOver) doesnt really work right because it only moves one pixel, then you need to roll off and roll back on… i am thinking there must be some do… while statement for the rollover action but i cant find it…

thx for help