I was using USB Overdrive for this, but I just uninstalled it because it was doing very funky things to my Mac OS.
I just want:
mouse wheel up = cmd+]
mouse wheel down = cmd+[
(avid media composer that is zooming in and out of timeline). I used to do it with razor mouse, but I hated their software, now I use a different mouse. Hopefully its possible to fire off macros from mouse wheel activity...
