Trying to scroll a MC menu on rollOver

CS3 / AS2.0
OK, I know I am missing something pretty simple but am drawing a blank…

I have a mc menu behind a mask. The menu has 12 buttons. The mask only shows 10. I have scroll arrows that work on press and on rollOver. What I want to add is a rollOver effect to the mc itself in the upper and lower regions that will automatically scroll up or down. Any help would be appreciated. TIA.

george_z