Logitech Marble Mouse

I assume the mouse is plugged in via a PS/2 port (not USB).

XF86Config-4

First things first, here is the correct settings for X:

Section "InputDevice"
    Identifier "Mouse1"
    Driver "mouse"
    Option "Protocol" "MouseManPlusPS/2"
    Option "Device" "/dev/psaux"
    Option "Buttons" "5"
    Option "Emulate3Buttons"
    Option "Emulate3Timeout" "50"
EndSection

This will set up the following behaviour:

Large left button

Acts as "button 1", a standard left click.

Small left button

Acts as "button 4", equivalent to a small scroll upwards on a scroll mouse.

Small right button

Acts as "button 5", equivalent to a small scroll downwards on a scroll mouse.

Large right button

Acts as "button 3", a standard right click.

Chord of both large buttons

Acts as "button 2", a standard middle click.

Works in...

Should work in any distro with XFree86 version 4.3. Tested and works in Mandrake 9.1 & 9.2 and Slackware 9.0.