I believe that in order to get at the innards of the new mouse,
you must remove the label on the bottom that says "Apple Desktop
Bus Mouse II"  There you should find two screws on either side.
I haven't tried it myself yet, but when I ran my fingernail
accross the label, these two divots appeared, and I can only assume
that these are the elusive screws in question.

cheers,
john