I gave a fast glimpse at your instructions and couldn't find any errors. Perhaps a couple steps I would have done otherwise, but it's okay. Hardest part truly seems to be with the xml files, but luckily that needs to be done only once.

I'm planning to include in package a configured xml, so it should ease out this step. I'm not just so sure about how "standard" it would be to install to user's home directory some stuff. Or should I just put the files in /etc/navit and let the user copy them from there?

/h