Steps of reproduction:
1) Have a mouse with more buttons and/or wheels (in my case Logitech NX80 with two extra buttons, a missing middle button and tilting wheel — has VWheel and HWheel functions)
2) Install evdev 2.0.99.3 (a.k.a. 2.1_rc3)
3) Remove mouse settings from 'xorg.conf'
4) Write a HAL .fdi file for the device according to 'man evdev' the example .fdi file, adding the 'input.x11_options.ButtonMapping' according to how the buttons should be mapped (e.g. "1 0 3 4 5 6 7 8 2")
5) Restart HAL
6) Restart X

Results:
* Button mapping is ignored ('xev' reports it as "1 2 3 4 5 <missing> <missing> 8 9")
* Horizontal wheel does not work and is not recognised by 'xev' (although it is detected by 'evtest')

Expected results:
* Button mapping working as is defined in the .fdi file
* Horizontal wheel working