kensington expert mouse pro

[Gregory Seidman <gss+debian@cs.brown.edu>]

I have a Kensington Expert Mouse Pro (it's a trackball), which has six
non-mouse buttons. These are a lot like the multimedia buttons on some
keyboards. I'd kind of like them to do something, but the USB driver
doesn't seem to register them (cat /dev/input/mice then pressing these
buttons gives no output; they also don't seem to give any keyboard input).

Is there any way to get them to send some keypress or something? I'd really
like them to act like extra keys on the keyboard that I can use xmodmap to
bind to whatever I like.

--Greg