With jsnr's fantastic help, I have installed very successfully on navigon 8410. The brilliant part is that you do not need to do anything to the innards of the machine.
Just get a new SD card (must be HC type) add the filles he sent me and add the sync files from skydemon, put card back, turn on and Skydemon miraculously works.
Its a great machine for running Skydemon.
PS With John's permission, if you send me a card I will xfer all files to get you started. BUT make sure you use Navigon Fresh to back up your machine befire you start.