lion: assign buttons on a Microsoft mouse

BetterTouchTool's "Normal Mouse" area allows you to assign functions to all kinds of mouse buttons and should work for you. It's free, too, so it won't hurt to try.

The author has issued a couple of recent updates to make it more compatible with Lion. There are still a couple of small things but I'm using it every day (previously with my mouse, now with my trackpad) and it's tremendously useful.

It turned out I just needed to install the most recent version of the MS drivers. Everything now works like it did.

The latest MS Drivers can be found at: http://www.microsoft.com/hardware/en-us/downloads (the versions in the MS Downloads Center, and in Google results are older which don't work with Lion)