Button Help

I’ve been trying to create these type of roll over effects like http://www.sandiaestudio.com/index_es.htm

I can do them using the standard tween but could someone point me to some source code that I could look at to create using A.S I tried the import tween thing, but couldn’t get it to work like this site, didn’t know if there is another way to do this in A.S?

Cheers