I actually just remembered what I meant by this TODO:
It was the idea to have xinput-properties for calibration that could be set via "xinput set-int-prop &lt;device&gt; &lt;X|Y|Z&gt; &lt;value&gt;"
This could then also solve the proplem of where to do the caching and stuff as it could happen within the user-session. Maybe also provide a calibration-program, that will take 10 seconds, start with a factor of 200 and divide it by 2 every second. That should work as calibration and also solve the cache-dir vs xorg.conf.d issue...