Right mouse button mapping on Linux Tablet PC

The pen button is much more useful as a right click than a middle, but it defaults to middle.

I thought I could fix it with xinput, like:

xinput set-button-mapping stylus 1 3 2

but this turns out not to work.

What actually works (from the Ubuntu bug) is:

xsetwacom set stylus Button2 3

I added this to the GNOME session (system->preferences->session).