You can patch firmware to select different 4 languages then in original configuration or you can flash basemap other then American. Changing basemap activates all languages available in firmware.

Flashing basemap is not a standard procedure, you need special firmware in rgn format, which contains basemap. All is ready in this file:
[Only registered and activated users can see links. ]

Do it all on your own risk. I know it works for SiRF version of 60CSx, I won't expect problems with MTK version, but I haven't tried. Credit to gps-forum.net.