It may seem a bit lot trivial, but the first thing most people gripe about after getting their finely tuned ride back after from trip to the local wrench jockey (read: you) is that they have to re-program the radio.  Be calm.  The first thing you need to do is refrain from choking them on the spot.  The next thing you need to do is find a code maintainer that will skirt the whole issue next time. 

A code maintainer keeps all the user programmed selections in stasis while the battery is disconnected — which happens quite a bit around the Toolmonger shop.  The procedure isn’t difficult.  Just connect battery clips to a 12 volt battery and plug the cigarette plug into the vehicles cigarette socket before you disconnect the battery in the vehicle.