Scrolling objects through mask

Hello everyone.
I have a question that i’m sure you’ll all know the answer to, however I’m really struggling to find out how to do it; I want to scroll a set of album covers on the y axis. I want it to work so that as you hover your mouse over the top of the pictures they go up (and out of sight through the mask), and when you hover over the bottom they go down…
Are there any tutorials for it on the site as I havn’t found one after a fair bit of searching.
Many Thanks,
Brent.