Button RollOver/RollOut Effects WITH looping on RollOver

I’m planning to use this tutorial, below to make a button:
http://www.kirupa.com/developer/mx2004/button_effect.htm

My question is how can I make it so that only on the rollover, the effect will keep looping?

Example: http://jump5.com/

On the right side, the navigation has this nice hover animation with the pointing arrow that continues to twitch on rollover.