Since it is considered an input device, you will want to make a section for it in your xorg.conf file. Bold line is the relevant one (change absolute to relative of course) - just including the rest for reference in case you need it.

Code:
Section "InputDevice"
 Identifier "pen"
 Driver "aiptek"
 Option "Device" "/dev/input/aiptektablet"
 Option "Type" "stylus"
 Option "Cursor" "stylus"
 Option "Mode" "absolute"
 Option "PressCurve" "0,5,95,100"
 Option "zMin" "0"
 Option "zMax" "512"
 Option "ZThreshold" "0"
 Option "USB" "on" 
 Option "KeepShape" "on"
 Option "debuglevel" "0"
EndSection
The max/min values may be different for your device, but the way xorg.conf works now is anything not set explicitly is set to 'auto'. So you may want to try a minimal config and slowly build up if needed.

Code:
Section "InputDevice"
 Identifier "pen"
 Option "Mode" "relative"
EndSection
EDIT => Oh, and welcome to JL by the way!