That sounds way too hard.
Most new DEI systems are capable of working on a manual transmission. They work kinda like an alarm. You do a routine that the system expects which is something like-- e-brake on while holding the brake pedal, pushing the r/s button to send the car into valet take over mode (remove your key,) then you open the door- close the door and lock. Which then the car responds to by shutting down. As long as the vehicle's current state is maintained (ie stays locked and the e-break up) it will r/s again.
really its only an extra relay for the clutch and door triggers for a r/s