You don't need patch to change languages or regional format.

If you have language files ready (Dutch.lproj, Spanish.lproj or what ever), copy them to right places on your phone and reboot. Now you can select them from menu: International - Language.
You can also select Regional settings from menu after you placed the files to right places.

Preferences.app will recognice new language files automaticly.

You are right, that goes for the language but not for the keyboard.