Let me know exactly what wiring diagrams you need and I will try to get them to you.
When I looked at the EPC earlier today (= electronic parts catalog) it only listed one main wiring harness number. But that might mean that if you order one now you only get the latest and greatest. Which is how BMW tends to operate.
But I did see the following standard, not retrofit, part nos for e90s with 6FL which I hadn't noticed before:
22.214.171.124.111 Lead, Aux+USB 385mm
126.96.36.1999.424 Holder, USB Plug ( a bracket of sorts)
188.8.131.52.361 Connecting Line, Hub/MULFII 3370mm (X17180-X17182)
184.108.40.206.360 Connecting Line, Hub/MULFII 2330mm (X17178-X17183B)
Don't know if that helps.
If you want to know what the "X" numbers mean (ie connectors) let me know and I will try to find out from the wiring diagrams.