Where the cable goes in is a grippy hole/clamp affair with two bolts that tighten it down. It clamps round the battery using the conventional way at the other end of the clamp assembly.

Does that shed any light? It's the best pic I've got I'm afraid. I did this in the dark back in December 2011!
Just for amusement, I found a new use for Adriana's bedside light...

Mike