I recently bought a Microsoft Sculpt Ergonomic Desktop keyboard and mouse set for use with my Mac OS X laptop. Unfortunately, Microsoft has dropped support for their keyboard and mice via their Intellipoint driver as of Lion, so to use some of the extra keys on the mouse, you have to resort to third-party utilities like Karabiner or BetterTouchTool.

This repo contains a private.xml file for use with Karabiner that remaps the following keys:

• Context menu key (the key to the right of the right Alt button) to the option key.
• Windows button on the mouse to either mouse5 (in case you want to use another tool like BetterTouchTool to customize further) or Mission Control. Note that BetterTouchTool is unable to recognize the Windows button on this mouse by itself, which is why is why the mouse5 remapping is useful.
• Back button on the mouse to Cmd + [, which is the default shortcut for back in many apps.
• Left scroll and right scroll to Cmd + Shift + [ and Cmd + Shift + ] respectively. This maps to previous/next tab in many apps.

After loading the private.xml file in Karabiner, you can use Karabiner's GUI to select which of these key remappings to use.