Table of Contents
Although the settings are described in the Video/XFree section I use this place to tell you that you have to enable PS/2 support in the kernel!
I deactivated it because there are no PS/2-Ports at the laptop, but the touchpad needs it... It took me 2 days to figure this out.
Even the scrolling works in vertical AND horizontal direction...
If you have problems getting this to work (it does definitely work in Opera), start xev in a terminal. Move your mouse above the window and press the horizonal scroll buttons. You should get "ButtonPress" and "ButtonRelease" events. The third line tells you which button is recognized: Perhaps button 8 and 9? If yes, that's the source of your problem.
Normally, vertical scroll wheel is buttons 4 and 5, and the horizontal is 6 and 7. You can check the physical-virtual button assignment by executing xmodmap -pp and change it via
xmodmap -e 'pointer = 1 2 3 4 5 8 9 6 7 10 11 12'
This command swaps the assignments of the buttons 8 and 9, making them be reported as virtual buttons 6 and 7 - what I needed to make it work here.