If it could be, where would you put the switch?
What's wrong with Clare's second idea, starting with "Put a switch"? (The beeper/bell? I doubt it but you can test that tomorrow by putting the parking brake on a little bit, enough to make the dash light come on, and see if a beeper comes on, with the car in drive and moving.)
You were willing to install a switch in the first place, he just told you where.