RoadKing

I just bought a 2008 RX350 and then decided to accept a position in Stuttgart, Germany. I will be taking the car with me. Does anyone know if it's possible to switchover to European maps on the GPS Nav? Is it a dealer only change, or something that can be done DIY? If dealer must perform, any ideas about what that will cost? Also, I've been reading some posts about 5.1 vs. 6.x firmware. How do I tell what I have? Thanks in advance for any suggestions for the newbie!