I've had the Corrado seats in the 81 for years now and always had the intention of hooking up the heaters. Then I saw this in the classifieds.
A little high on the price but when it falls into your lap you just have to buy it (plus a new switch alone list for about $150 )
Turns out that it is from a 92 cabby and I have a 92 with heated seats and the Bentley for that car that I could use to help identify wires.
The wiring sockets on the corrado seats didn't match the plug from the Cabby wiring, But the seat wires colors were the same as my 92's seats wires, and by using the wiring diagram and their position in the socket I was able to verify that they were the same wires (without having to tear open the seats to trace out the wires).
So last night I spent crimping and soldering two 6 pin plugs and two 6 pin sockets from Radio Shack.
Today I should have it all hook up and have a warm arse.
So the bottom line is that if you already have heated seats in your car, the wire color code for any other heated VW seat that will fit in these cars should be the same and you would just have to make up a new connector (really only need 4 pins)
If anyone wants some pics let me know in the next hour or two and I can take some.
PS: one final note the wiring diagram in the Bentley for the 92 cabby heated seat does have an error two of the power leads for the switch that it shows are jumpered together are actually separate which makes sense since one is for the lighting and should be connected to the dash light circuit and the other is for control and should be powered from a circuit that is only hot with the engine on.