Depending on what type of touchpad it is (eg alps, synaptics), you can change a bunch of parameters if you use the Xorg-7.4 extension.
If you use Xvesa, you might be able to disable the touchpad and use the pointing stick (this is what I do) by choosing the mouse parameters in.xsession.
On my machine:
Xvesa -br -screen 1280x800x32 -shadow -2button -mouse /dev/input/mouse0 -nolisten tcp -I 2>&1 > /dev/null = pointing stick
Xvesa -br -screen 1280x800x32 -shadow -2button -mouse /dev/input/mouse1 -nolisten tcp -I 2>&1 > /dev/null = touchpad