Use existing OBDII hardware to plug into any one of the three Tesla OBDII Busses.  Plugs in-between the existing harness connector at the back of the driver's right elbow rest, exposes a male ODBII connector, as is found under the dash of a typical car.  Use your existing OBDII readers (including the bluetooth ones)  and software (freeCAN, ODBII, Torque) to talk to components on the bus.