http://www.linux-gamers.net/modules/wiwimod/index.php?page=HOWTO+Mouse+Buttons

http://linugadgetech.blogspot.com/2008/08/review-logitech-lx8-wireless-laser.html

After some head banging and scratching, I took ideas from each and came up with this in my /etc/X11/xorg.conf file.

I added this section:

Section “InputDevice”
Identifier  “Mouse[5]”
Driver      “evdev”
Option      “Device” “/dev/input/event5″ # (cat /proc/bus/input/devices)
Option      “Name” “Logitech LX8″
Option        “ButtonMapping”   “1 2 3 4 5 8 9 6 7″ #RH
EndSection

and replaced the system configured mouse entry in the ServerLayout Section like this:

Section “ServerLayout”
Identifier    “Default Layout”
Screen        “Default Screen”
InputDevice    “Generic Keyboard”
#InputDevice    “Configured Mouse”
InputDevice    “Mouse[5]”
EndSection

The key was using Linerd’s button mapping option with Linux-Gamers’ xorg.conf section.
Be sure that you get your own event number for the line: Option      “Device” “/dev/input/event5″  from cat /proc/bus/input/devices . Mine was 5, yours may be different.

Also I did not have success until I removed my orignal mouse. At first I had them both plugged in and I think it was messing with me.