The column, oddly enough, is a Ford column. I used an early 90's Ford adapter in my GTXR2.
It fits, but the contact wheel on the bottom required significant modification to mesh with the Capri bits. I think I ended up making a wood spacer.
There may be better options out there.
I sat down & reverse engineered the cruise control system one night. I forget the exact details, and I doubt I made notes. So here's what I remember:
There are 3 wires with slip-rings to the steering wheel. These 3 wires operate the horn + the whole cruise control system.
I don't remember the pinouts.
The cruise system uses only two of the wires, despite there being 4? 5? switches.
It uses a crude serial system. Each switch is connected to a resistor of a different value.
The cruise module reads the button presses on the same two wires, and the different resistances correspond with a different button press.
I planned on adding simple pushbuttons to my steering wheel, with the appropriate resistors, to retain cruise despite the aftermarket wheel.
You'll have to take the stock buttons and measure them with an multimeter to get the appropriate resistance values.