The idea described here was originally developed in a conversation on the Nikon-Digest mailing list. While developing the release a dutch nikonist put his F-501 at risk and another nikonist from Portugal endangered his MC-12A remote release. Thanks to these brave men :O)> the structure was revealed and it turned out to be very simple. MC-12A simply fires the camera by short-circuiting the two pins on the release socket. Autofocusing and metering is done by connecting three diodes between these pins. 

Here's a drawing of the connection, I've used two switches in my system - one fires and one focuses/meters. 

The biggest problem was to find the connector to the cameras socket, but that was soon solwed. I've used a connector made out of a D-connector used in computers. Surprisingly the holes in a D-connector fit exactly the pins on the camera. The only problem is to cut a piece that has two "holes" and fits the camera socket. I managed to cut a working version on second try. I then added about ten centimeters of thin wire to this connector and fitted a pair of cheap connectors on the other end. The reason is simple - by attaching this thin wire to my camerastrap I can avoid accidentally pulling the connector off the camera. Besides, now that there are connectors between the plug on the camera and the remote control, I can add different lengths of cable when I need a longer remote. I've used a ten meter cable made out of cheap wire (about 1mm in diameter) and it works great.
Before you attach all the wire permanetly, try the connection. Those diodes only work in one way (like diodes do...) and so the focusing/metering only works when the wires are connected one way, though the shutter release works both ways. But there is nothing dangerous in connecting the wires wrong - the worst thing that can happen with the remote is short-circuiting, and that only fires the camera - nothing more.
I assembled my remote to an empty film canister. I attached the switches on the cover and the wire comes out thru the bottom of the can.

PARTS:

• two switches (non-lockable), preferably different colors
• 3 diodes, type: 1N4148
• enough cable (with two separate wires)
• filmcanister or some other box for the remote release
• connectors (for eample abiko)

Assembling the remote only took a short while and the result is a fully working electrical remote control with AF. The princible can work in other Nikon bodies also, but for sure it works on F-801 and F-501. I believe that it should work on the close relatives of these bodies also - like the 801s etc.