Tired of my MX900 scroll wheel not working (and it was getting long in the tooth) I got a new MX1000 today. To get the scroll wheel to work I used the following entry in my /etc/X11/xorg.conf file

Section “InputDevice”
Identifier “Mouse[1]”
Driver “mouse”
Option “Device” “/dev/input/mice”
Option “Protocol” “ExplorerPS/2”
Option “Dev Name” “Logitech USB Receiver”
Option “Buttons” “12”
Option “ZAxisMapping” “11 12 10 9”
Option “Resolution” “800”
Option “Emulate3Buttons” “false”