If your car has remote door locking, you can pretty much do whatever you want with a few diodes.
You could hook the ign wire of the empeg up to both the ign and the + puls of the door lock, seperated by 2 gen purpose diodes (connect the banded side of both diodes to the empeg and the other side of each diode to each 'ign' wire) like a 1N4001 or similar (these have 1A limit so check how much current goes thourgh the ign wire).
Each time you push the lock button of the remote, the empeg will get a ign puls putting the unit in standby. If your remote has a seperate button for lock / unlock you don't even have to unlock the door first (safety issue, although it's only for a few secs)
If you find it too hard to find the + wire of the doors, you could use something else that turns on with the remote (like interior light, turn indicator, headlights etc). Shouldn't be hard to do.
If your car doesn't have a remote, you could get one of those universal remote controlled door locking relays and use that instead (heck, you can even hook it up to the doors at the same time).

Frank

Edit: I've never checked how long the puls has to be for the empeg to turn into standby. If the puls from the central locking isn't long enough, hook it up to a relay with a capacitor over the coil to keep the relay closed for a few secs.