I would love to help to Improve the Linux Driver Support but i can only inspect the Laptop and it's behaviors till Tuesday.

And I get first wired result if i try to usbhid-dump the tablet:
sudo usbhid-dump 002 004
Failed to retrieve interface #0 report descriptor: Pipe error (ERROR_PIPE)
or do i need to write the output direct into a file?

It semes that the using from the xf86-input-evdev drivers work for Mypaint, and that would be the key point for my friend. I would like to use the xf86-input-evdev driver till there is an official support for that tablet. But i still have no idea were i have to set the used driver.