Bonjour Jean-Claude,
Welcome to this board (and the Zaurus world)!
Look for a program called KeyHelper, with this tool you can "redefine" your keyboard so that you can type the French accented characters...
You can find it here:
http://tbox.jpn.org/linuzau/keyhelper/PM me and I'll send you my config file if you're interested. You can also do a search on PDAFrance Linux forums (or on this board, for that matter) using "Keyhelper", this has been discussed before and there are some interesting posts.
You'll need to make sure that you have the proper fonts installed first (by default, the Japanese fonts don't let you display accented characters, so you have to install other fonts), but otherwise I think it should work on your 3100 as well as it does on my 3000.
