You should however make a copy first in case something goes wrong, but do not place the copy in the nokia_vndr folder or it will stop your phone from booting.

After modifying the rx-51 file, type `setxkbmap' to apply any changes for English keyboards, `setxkbmap de' for German keyboards, etc. If you see an error you should replace the rx-51 file with your backup - if you don't the device will fail to boot and you'll have to reflash it!