The wiring diagram of the paper user guide earlier than 141116 is wrong.
The user guide later than 141116 was corrected.
Wrong IBUS wiring
Corrected IBUS wiring 
The wiring diagram of the paper user guide earlier than 141116 is wrong.
The user guide later than 141116 was corrected.
Wrong IBUS wiring
Corrected IBUS wiring
I have an e90 Steering wheel in my e46. Would the Setup in the bottom image with BSGr and Jexd work to convert this signal to control the e46 ibus stereo?
Hello
The output of E90 steering wheel control from the button is resistive as this post.
http://www.exinterface.com/an1043/
Exd can read the resistive signal, and Exc can output IBUS signal to control the radio(BSGd).
You do not need BSGr, you need only Exd to control IBUS stereo.
Thank yhou