I use gentoo as linux distribution,. but I'm pretty sure that my solution can work. First your device section of /etc/X11/XF86config must be:
Section "InputDevice"
Identifier "Mouse1"
Driver "mouse"
Option "Protocol" "ExplorerPS/2"
Option "Device" "/dev/input/mice"
Option "Buttons" "7"
Option "ZAxismapping" "6 7"
EndSection
You must install imwheel :
http://jcatki.dhs.org/imwheel/
and I you $HOME/.xinitrc (if you launch your X server with startx, or you can add this to your starting script for your X session manager:
xmodmap -e "pointer = 1 2 3 6 7 4 5"
imwheel -k -b "67" &
Finaly, In $HOME/.imwheelrc :
"(null)"
None, Up, Alt_L|Left ,1
None, Down, Alt_L|Right ,1
"^Mozilla.*"
None, Up, Alt_L|Left ,1
None, Down, Alt_L|Right ,1
(itś work with firefox browser)
Good luck!