I spent several years in Japan while in te military. Although I didn't own a car while there (why bother with the wonderful rail system?), I was elected as the designated driver whenever we went anywhere as a group, as I was the only one to have the guts to speed down the narrow Japanese roads with traffic. I even got used to shifting the opposite direction.

The best way to learn is to find a relatively empty parking lot and drive around for a while. Also, see if your local Saturn dealership has a left-handed drive car available (Saturn builds them for postal service employees).