When you enable the French keyboard, you can access the extra French characters by clicking on button on the right bottom.

Another option is to use the Asian version which let you input the text using the installed keyboards on your windows mobile. The only feature you will miss in the Asian version is the French interface.

Download the latest Asian version from here:
[Only registered and activated users can see links. ]

After the usual installation process, copy any font you like to the directory \Storage card\Garmin\Font and rename the font to Chinese.ttf . The program won't work without this file. Now run the program and find your way to the page where you set the language to English and Enjoy!!