Problem with using tween class

Hi guys,

I have a number of movie clips on my stage. Which on(rollOver) I would like them to become bigger.

I have written the code for the Tween class and would like to run it in a function().
So, basically what i want is a function() which I can call so that when i rollover the movie clips they become bigger. and rollOut they go back to their original size. How do i do that?