1. Edit /etc/X11/xorg.conf, add the lines,
  
 Section "InputDevice"
       Identifier  "Configured Mouse"
       Driver      "mouse"
       Option      "CorePointer"
       Option      "Device"              "/dev/input/mice"
       Option      "Protocol"            "ExplorerPS/2"
       Option      "Emulate3Buttons"     "on"
       Option      "Emulate3TimeOut"     "50"
       Option      "EmulateWheel"        "on"
       Option      "EmulateWheelTimeOut" "200"
       Option      "EmulateWheelButton"  "2"
       Option      "YAxisMapping"        "4 5"
       Option      "XAxisMapping"        "6 7"
       Option      "ZAxisMapping"        "4 5"
 EndSection
 
2. Edit /etc/hal/fdi/policy/mouse-wheel.fdi, and add the lines
  

 true
 2
 6 7
 4 5
 4 5
 true
 
Reference
 
http://www.thinkwiki.org/wiki/How_to_configure_the_TrackPoint#Most_common_Features
http://www.thetacticalnuke.com/2008/ubuntu-810-intrepid-ibex-beta-on-t61/
 

10.10

1. /etc/X11/xorg.conf

Section "InputDevice"
       Identifier  "Configured Mouse"
       Driver      "mouse"
       Option      "CorePointer"
       Option      "EmulateWheel"        "on"
       Option      "EmulateWheelButton"  "2"
       Option      "YAxisMapping"        "4 5"
       Option      "XAxisMapping"        "6 7"
EndSection

 
2. http://www.linuxidc.com/Linux/2010-07/27132.htm
 
System -> Preferences -> Pointing devices
 
TTPS/2 IBM TracePoint -> Use button 2 as Wheel emulation.

3. http://forum.ubuntu.org.cn/viewtopic.php?f=126&t=227334&start=0