WinCE on Roadmate 2200T

I just saw an article in a French language web forum that told how to
get to the WinCE desktop in a RoadMate 800. The secret code was
entered using the + and - screen keys for the unit's volume. The
combination was ++--+-. Apparently the RoadMate 800's volume is on
the main system screen. Once you do that, the 800 shows the WinCE
desktop with the recycle bin, folder, My Computer, etc. Of course,
the volume on the 2200T and the 2000 isn't controlled that way.

Does anybody know of a way to bring up the WinCE desktop on a 2000 or
2200T? Trying the same combination using the zoom-in/zoom-out screen
buttons doesn't work.