I'm planning on doing this for my next project, so I dug up a little more info. I took a couple of pictures of my SBLive:
http://mp3box.2y.net/temp/livevol1.jpg
http://mp3box.2y.net/temp/livevol2.jpg
I belive a switch between the top and the bottom would be volume up, and a switch between the middle and bottom would be volume down.
Hope this helps you.