a custom shop might do it, but with no paperwork/warranty etc.
I do it for a living, and I was always pissed that I put in remote starts all day, and I don't have one! I did not want to put it in without a safety feature, so I made my own "intellistart module" using 2 relays and a 10 amp manual reset breaker. I used a momentary switch to activate the remote start while the vehicle is still running, and hooked up the relays and breaker (I put the breaker next to the momentary for easy access) so that I must leave the car running in order to open a door without the breaker popping. If the breaker pops, I cannot R/S the vehicle. But if I use the R/S takeover, take the key out (vehicle still running), get out, shut the door, and then shut off remote start with key fob, then I can R/S the vehicle. if someone opens the door without the ignition on, the breaker pops, and I cannot R/S it!
the only way it could remote start in gear is if someone put it in gear by reaching in when the doors are off, or the top is off/windows down, etc. I just don't leave my windows down when parked, and when I take my doors off, I disable the remote start, and don't remote start it!
here is the schematic for my own intellistart. I assume no responsibility, nor do I guarantee the degree of safety this system provides, use at your own risk, etc. etc. yada yada yada...