i think pin 7 and 8 are swapped, i could be wrong though. ill try to dig up a thread i found with the info.
* EDIT *
Found this article detailing the building of a cable:
http://www.new-sweden.com/forum/showthread.php?t=959
It appears pin 7/8 are bridged.
I have mine on order still for my 06 325xi so i haven't got to test yet
