Maybe that could help:

Navi retrofitting guide: http://www.xoutpost.com/articles/all...system-x5.html

New cabling for Nav (cheap): BMW E53 X5 Navi Kabelbaum Für MK3 MK4 bm54 16:9 Vers. | eBay

Good luck!

If you need any help with the Austrian selling the cabling let me know. I am located in Austria too.