MFD is just a different name for a RNS system, it stands for Multi Functional Display i think.
Anyway.. just read this thread
http://www.seatcupra.net/forums/showthread.php?t=139255 for all your information. It applies for the RNS310/315 systems as well because they use the same shape (double-din format with curved edges).
The fascia surrounding you will need afterwards is also in that thread. If you want to know more about interior colour codes i could
help you out but the basic information is in there!