Don't know if any is still following this thread but I happened upon it a couple days ago as I was looking to internalize my wifi adapter. I decided to follow the advice and remove the memory card slots on the front of my 360.
I have one of those new "n" wireless adapters with the two antennas. I tore it apart and cut the usb end off. I wired up the four wires to the points shown on the pic above.
It works!!!!! My wireless network popped up full signal.
I modified front of the 360 to have the antennas sit right in front of the memory card slots behind the face plate... worked out really well since there are two holes for the wires to pass through and all I had to do was cut a little plastic for the big antennas to rest there
Now the bad news... While placing the wifi unit I somehow tore the red wire right where it joins the mini connector on the wifi unit. Rather than dealing with it I decided to hard wire it to the board. Would of went fine but I lifted a pad. Don't ask me how I am still pissed.
Anyways I spent a few hours trying to solder to alternate points only to get it to work for a little bit then it would stop. Such a noob mistake but that's life.
Good new it works. Bad news is I have to wait to get a new adapter to try again but when it is done it will be nice and I won't lose the back usb which is going to be converted to a kinect plug in the near future.
I could have sworn I posted my findings on this here ages ago, maybe it was elsewhere, it's easy to make a dipole, or solder on and extend to a full-wave antenna (or SNA connector in my case) I did it the day I got my slim as the .N had terrible reception (I got it about 2 weeks after release) I use it all the time using just the connector and nothing attached and it still works better than the stock PCB-crappy antenna. I was wondering if anyone had actually identified the chipset as according to common-law they are meant to stick to a standard (like the DATEL/memory stuff and controllers) it would be stupid no to. The connector appears same as internal MU and kinect pinouts, so should be easy to figure-out how to add a different NIC
RGH could solve any driver issues potentially also. Myabe if M$ made them perform better and didn't over-price them we wouldn't be here but as it is....