Finally the application panel driver is ported to linux 2.6. The latest version is available from the SourceForge project homepage.
Basically cleaning up the code a little and adding a few more #ifdef's did the job. I was surprised by the ease of use of the new kbuild system. However I still can't understand why people are using 2.6 yet...
The updated driver also contains some documentation on how to configure udev to work with the kernel module. The user-space utilities did not change at all, so you can use them both with 2.4 and 2.6 kernels.