Addition functionality to scroller

Hello

I’m trying to do something similar to
http://www.galileodc.com/.

I came across a nice little tutorial here at kirupa
http://www.kirupa.com/developer/mx/infinite.htm

Although I’m stumpted as to how they get the scoller moving one space over and getting a rollover effect working together with the mouse over scroller. Does anyone know of a better tutorial perhaps?

Sandman9