You can actually get the mouse to work with two
buttons. It isn't very highly documented, so it's
not that easy to find in the Maya literature. It has
been a while since I actually did it, but search through
the installation and manual literature, and it says
exactly how to do it, just a few obscure resource texts
to alter slightly. From there, I think you just have to
use a key combo with a mouse button to get the effect of
a third button. It seems like a pain, but once you get
the hang of it, it's no problem, since if you get experienced
with maya you'll be doing all kinds of key combos all the time anyways. Hope that helps, I haven't gotten the "third button/scroll
wheel" to work with anything except expose, which it works pretty
well for.