There's a lot of mis-info out there!
Key on-off works, but a kill switch would be a bit safer.
If you had wiring schematics, you could make up a circuit that would be reversible and wouldn't require splicing/cutting (by removing/accessing the right pins from existing connectors).
Anyway - good luck during the break-in. I'll probably never buy a new car, so won't have to go through that torture!
