Since Microsoft still doesn't let you remap the buttons on the pen, I started using this great little toolbar. You can create custom toolbars for any program. This is one I made for Mudbox. It lets me use this program without a keyboard.
http://forum.tabletpcreview.com/threads/toolbar-creator-v-2-2-beta-available-for-download.63014/
http://forum.tabletpcreview.com/threads/toolbar-creator-v-2-2-beta-available-for-download.63014/