The cruise control I have built in is linked to the ecu VSS signal, clutch and brake switch and some ecu wires. It is not linked to the cluster at all. You will have to investigate what cruise options come with your engine/ecu and find out what vss the ecu would like to see. Come to think of it, that might be also important for your ecu's torque control. I've heared of TDI's that wouldnt run full torque without the speed signal linked to the ecu. In that case you will have to make 2 speed sensors. 1 for the cluster, 1 for your ecu (probably both on different signals/distance)

my cluster (running empty gas tank in this picture, but I drive mostly LPG lol)