This is how you build a harness to simply plug in your new combox module without cutting any wires on your car and without re-pinning an connectors on the car (only applicable to cars with CIC or CIC retrofits of course..). This particular guide is only for cars with TCU's ONLY, but I can help with MULF systems as well.
Here's the basics of what you need:
Combox side:
1 x 61136913644, BMW, connector, 26 pin
1 x 61136913626, BMW, socket housing, 26 pin
~15 (order 20) x 928999-6, TE, female pins (BMW has these too, but they are like $1 a piece, easier to just buy them from onlinecomponents.com. Exact same thing
22 AWG wire
TCU side:
1 x 37758, Kufatec, 54 pin connector. socket housing is included
~15 (order 20) 1-928918-1, TE, male pins (BMW has these too, easier to just buy them from onlinecomponents.com. Exact same thing)
Here's what it looks like in the end:

Combox end. The blue'ish green connector has the pins labeled so you can use that to figure it out

TCU end below. Notice I wrote pin #'s on connector--bottom is 37, top is 54. On the next row down (towards the floor in the pic), bottom pin is 19, top is 36. and Bottom row, bottom is 1, top is 18

And here is how it is wired:

I'll post more detail on how to crimp the wires, etc. when I have more time
Here's the basics of what you need:
Combox side:
1 x 61136913644, BMW, connector, 26 pin
1 x 61136913626, BMW, socket housing, 26 pin
~15 (order 20) x 928999-6, TE, female pins (BMW has these too, but they are like $1 a piece, easier to just buy them from onlinecomponents.com. Exact same thing
22 AWG wire
TCU side:
1 x 37758, Kufatec, 54 pin connector. socket housing is included
~15 (order 20) 1-928918-1, TE, male pins (BMW has these too, easier to just buy them from onlinecomponents.com. Exact same thing)
Here's what it looks like in the end:

Combox end. The blue'ish green connector has the pins labeled so you can use that to figure it out

TCU end below. Notice I wrote pin #'s on connector--bottom is 37, top is 54. On the next row down (towards the floor in the pic), bottom pin is 19, top is 36. and Bottom row, bottom is 1, top is 18

And here is how it is wired:
That's it. The only elusive part is the black connector from kufatec. It takes a full 4 weeks to get them in.. so I ordered 3TCU (BLACK)-------------------Combox (BLUE GREEN)
Pin---Description--------------Pin---Description
1----Mic(pos)------------------------25----Mic(pos)
4----AUX-GND-----------------------10----AUX-GND
15---Crash Sig.----------------------7----Crash Sig.
17---30 Power+ 5A------------------2----30 Power+ 5A
18---30 Power+ 10A-----------------1----30 Power+ 10A
19---MIC(neg)-----------------------12-----MIC(neg)
21---MIC Shield----------------------11-----MIC Shield
23---Shield---------------------------22-----Shield
31---SOS sig.f Button---------------18-----SOS sig.f Button
33---Wakeup-------------------------15-----Wakeup
36---31 GROUND(neg)--------------14----31 GROUND(neg)
37---emerg. Speak.(pos)------------21----emerg. Speak.(pos)
38---emerg. Speak.(neg)------------20----emerg. Speak.(neg)
50---emerg. butt LED----------------17----emerg. butt LED
54---GROUND-
I'll post more detail on how to crimp the wires, etc. when I have more time