Panning between six different background pictures

Being a really nice day here in the south west of england my head is really boiling and I can’t think this one out just now. Anyone that can help and I’ll be really really happy! :crazy:

Basically, I’ve got six different pictures as a background for my website.
Like so:

So: What I want to do is to have six different buttons that controls the panning of these six pictures. The problem is how to get from x to y, say from bottom right to top left. If the user press a button that is assigned to that background picture I want the pictures to be panned from its origin and sweep across the middle and then end up on the to left (hope this is clear).

Can anyone help / come across something similar I would be very grateful!