Class question

If I have a ball movieclip in my library, and I want it to be able to access methods in a ballClass.as file, I right-click and select linkadge and fill in the AS 2.0 class name. Great, my ball now has access to functions in my ballClass class file.

But how do I allow my ball to access the ballClass.as class file without selecting it in the linkadge,? e.g. if I want a bouncy ball and a hard ball but still want to use the same graphic (I could of course duplicate the movieclip in the library and change the linkadge, but that would needlessly bloat my .swf)