So you have a touchscreen, and a 'modern' X11 installation.
Your 'modern' X11 knows that actually configuring devices is something that people who live in caves do. 'Modern' X11s use HAL!
Unfortunately, the nice 'modern' X11 installation is borked. It's talking to HAL which is telling it to use inputs/event0. Which doesn't actually exist.
So the question is: How do you tell it to use /dev/inputs/event2 which is a working touchscreen?
Ahh, you might ask. What you really do is spend far too much time searching google and eventually arrive at:
<?xml version="1.0" encoding="ISO-8859-1"?>
<match key="input.product" contains="Touchscreen">
<merge key="input.x11_driver" type="string">evdev</merge>
<merge key="input.x11_options.SwapAxes" type="string">true</merge>
<merge key="input.x11_options.InvertX" type="string">true</merge>
Which you install in /etc/hal/fdi/policy/touchscreen.fdi
Of course. it was obvious from the very start that this was the thing to do, no? And the documentation has zero mistakes or misspellings in it. A remarkable end it achieves by being non-existant.