I had the choice of loading North American maps or European maps when I took delivery of my US-spec car in Germany.
The delivered it with the North American maps, depsite my request for the European set, but were able to re-flash it in about 30 minutes.
Depending where you are in Switzerland, you may find a closer dealer to Ramstein. My dealer is located in Bavaria (Pressath) and is familiar with US spec cars.
2009 M3 E93 Silverstone II over Bamboo: 6MT, Tech, Premium, Cold, Premium Sound, Ipod, 19'' Wheels, OEM Exhaust Mod.