I opened up the controller during the weeken to see what it actually does. The controls consist of mechanical switches which i suppose are connected to the seat motors directly. I need to measure both the voltage that is going through the wires and the current. Me initial idea was just to have the microcontroller feed the wires directly but if there is a lot of current i probably need an array of relays.

Further more, there was no ground connection in the controller module so i need to find this somewhere else...

Anyhow, parts are ordered and planning continues :)