Anyone care to translate?
No need.
Go to my website below and you will find the instructions in English as well as much more pics. Including info for cars with sunroof.

And just contact the companies mentioned before and ask if they can deliver the right thickness.
From this company you can even order samples.
http://www.cyber-bridge-marine.com/a..._headliner.htm

ENGLISH: (all from my website)
description/instructions
http://bimmer.roadfly.com/bmw/forums/e32/5715438-1.html
pics
http://bimmer.roadfly.com/bmw/forums/e32/5717037-1.html
sunroof
http://www.headlinerkit.com/bmw/index.shtml