For this release, Ubuntu switched away from hal/udev¬† and went back to the old xorg configuration (I like this much better). There have been improvements and changes to the xorg.conf since we last used it (8.10 wow that’s been a long time!)¬† so now instead of putting everything in one giant /etc/X11/xorg.conf file and risking a single typo from breaking your x-server, we can put files in xorg.conf.d . This splits up configuration files so they can be more easily organised.

Here are the steps to get the middle-mouse scrolling again in Ubuntu 10.04, the Lucid Lynx. This should work for just about every thinkpad, and this same procedure will work in any Linux operating system using the xorg.conf.d method (if the /usr/lib/X11/xorg.conf.d/ folder doesn’t exist, then your distro is probably not using this method).

Begin by opening a terminal, and editing/creating the configuration file:
sudo gedit /usr/lib/X11/xorg.conf.d/20-thinkpad.conf

Now, paste in the following contents:
Section "InputClass"
Identifier "Trackpoint Wheel Emulation"
MatchProduct "TPPS/2 IBM TrackPoint|DualPoint Stick|Synaptics Inc. Composite TouchPad / TrackPoint|ThinkPad USB Keyboard with TrackPoint"
MatchDevicePath "/dev/input/event*"
Option "EmulateWheel" "true"
Option "EmulateWheelButton" "2"
Option "Emulate3Buttons" "false"
Option "XAxisMapping" "6 7"
Option "YAxisMapping" "4 5"
Option "EmulateWheelTimeout" "200"
EndSection

you’ll probably want to delete and re-type all of those quotation marks, I don’t trust wordpress’ “code” tags to keep those straight. Then you’re ready to save and close the file. A quick restart of X (reboot your computer, or ctrl-alt-backspace if you enabled that in System > Preferences > Keyboard > Layouts > Options > Key Sequence to Kill the X Server > check the box. )

The line “EmulateWheelTimeout” is not absolutely necessary, but it does help prevent things from being randomly pasted everywhere whenever you try to scroll (for some reason people think it is funny to automatically map middlemouse to “paste”).

Sources: http://www.eastwoodzhao.com/thinkpad-middle-button-scroll-ubuntu-linux-10-04-lucid-lynx/
http://fedoraproject.org/wiki/Input_device_configuration
http://www.thinkwiki.org/wiki/How_to_configure_the_TrackPoint#xorg.conf.d
http://blog.aliencam.net/articles/ubuntu-9-04-setup-guide/ (yes, I just cited myself.)

–aliencam