USB Touch Screen setup:
 
The version of USB touch screen driver composed of two parts. tkusb.ko, a kernel module to
represent a serial interface to user programs. and a XInput module unitouch_drv.o.
 
The following are steps:
1. Copy tkusb.ko to a directory, I'll assume /usr/irtouch.
2. run: cd /usr/irtouch
3. copy unitouch_drv.o to /usr/lib/xorg/modules/input. 
4. Add one line to /etc/rc.d/rc.local: 
   insmod /usr/irtouch/tkusb.ko before the line startx. 
5.Setup the /etc/X11/xorg.conf as follows:
a) Add one line:
InputDevice    "irtouch" "SendCoreEvents"
to Section SererLayout.
 
b) Add one section InputDevice as follows:
 
Section "Inputdevice"
              Identifier "irtouch"
              Driver "unitouch"
              Option "Device" "/dev/tkpanel0"
              Option "AlwaysCore"
              Option "screenno" "0"
              Option "MinX"  "70"
              Option "MaxX"  "4055"
              Option "MinY"  "4095"
              Option "MaxY"  "90"
              Option "UntouchDelay" "3"
              Option "ReportDelay" "1"
EndSection

Possbile problems:
1. verMagic mismatch
run modinfo tkusb.ko , the following are output in my computer
author:         IRTOUCHSYSTEMS	
description:    Infrared USB TouchScreen Driver
license:        GPL
vermagic:       2.6.4 preempt VIAC3-2 gcc-3.3
depends:

 
compare the line vermagic with output from your kernel module. If the output don't match, please send your output to me.
 
2. after run insmod irtouchusb.ko and before entering X11, run
od -h < /dev/tkpanel0, if you can see output, the installation is right, or something bad happens, such as , you haven't plug touch screen or touch screen is bad.
If you encounter any problem, please don't hesitate to let me know