Can't believe I found this: I very strongly recommend that you d/l this immediately!
http://www.mirrorcreator.com/files/1CX1GUFV/SDUnlock_for_c220.zip_links new link
PW: navitotal
Directions for Simple Unlock for c230 and possibly other 320x240 devices:
The directions are simple. Unzip the files into a folder on your computer. Copy the folder "Script", the file "autorun_ABC" and the text file "autorun_ABC" onto your SD card. Those files are for the unlock.
Put the SD card into your mio and do a ...