Have you tried searching? I've seen this topic posted several times before with a link, you could try that.
As far as doing it, I've done it several times and honestly having pictures or seeing someone else do it really doesn't help much. If you know how to use a dremel, have a good assortment of bits and know how to use them, it's pretty self explainitory.
Myself I just use a cutting wheel and high speed cutter to remove the material and cut the battery slots. You just cut half the center channel out, extend the slots towards the middle, and chamfer them. I oversize them a little to move the batteries down as well as in.
It would be a much cleaner job if one had access to a drill press.