On the 156 you press the INFO button when the car is NOT moving, and there is a menu called LANGUAGE. Go into this, and find the language you want. I tried to learn Italian with it, but I got worried whenever a warning popped up which I couldn't understand!!
Thanks I found it. Press trip and the bottom right menu option is for settings. This way you can access language choices. The difficulty is to understand the word "settings" in the active foreign language.
Unfortunately i don't have the car manuals can can't find them on the web.