Section "InputDevice"
    Identifier  "Intellimouse"
    Driver      "mouse"
    Option        "Protocol" "ExplorerPS/2"
# Change the device to point to the correct location!
# I use the USB connection
    Option        "Device" "/dev/input/mice"
# My Wireless Intellimouse Explorer 2.0
# has 9 buttons counting the left/right tilt of the wheel
# although I haven't succeeded in using the left/right 
# tilt for anything yet.
    Option        "Buttons" "9"
# The wheel needs to be the "last" two buttons (bug?)
    Option        "ZAxisMapping" "8 9"
# Executable script /etc/X11/xinit/xinitrc.d/xmousebuttons contains:
# /usr/X11R6/bin/xmodmap -e "pointer = 1 2 3 6 7 8 9 4 5"
# Result is the scroll wheel and back/forward thumb buttons work.