The firmware will make all the changes proposed in this forum thread on its own, after which the camera will become a fully European model that can be upgraded to the latest firmware version for this model.
Read this blog post, download the service firmware, and simply update your camera through the web interface. Your camera will be permanently converted to the European model.
these firmware have a digital signature, file changes are not impossible, you can change the loader on the programmer and fill in the old, hacked version of the firmware
If your camera is still working, you just need to flash it with the suggested firmware from this article
after that, your camera will become European forever.