There is a way to make Linux autodetect wheel mice in the PS/2 port (which Knoppix currently can't do). The solution is a program called gpm. Unfortunately there is a bug in the current version of gpm (1.20.1) so it doesn't work yet. There will be a new release of gpm in the fall where this is fixed, so the next Knoppix release could incorporate this very important convenience feature.

Anyhow, here's how to do it:

- install gpm and give it the following parameters

input port: /dev/psaux
type: imps2 (so gpm does its autodetection magic)
replication type: imps2 (any other setting will not work)

- in xf86config set the following

"device" should be "/dev/gpmdata" instead of "/dev/psaux"
"protocol" should be "ImPS/2"
zaxismapping and the rest should naturally also be set properly

That's it. I have a self-modified gpm executable with these settings on my laptop and it works great. When I boot without an external PS2 mouse the "knob" works automatically. When I boot with a wheel mouse, scrolling works without any problems.

More information can be found here. X.org's xserver might do proper mouse autodetection in the future, which would eliminate the need to use gpm.