The simple answer would be to disable the central locking altogether, the vacum pump in the 190 is under the rear seat. Disable this, and when you unlock the drivers door, only the drivers door will open, the rest of the doors and the boot lid will need to be done manually. However by doing this you will lose the locking function on the petrol filler flap.
Another way would be to consult any car alarm installer. They have loads of alarms that lock and unlock car doors...even start the car using the remote. They would be able to help you for sure.