Hey there! Funny thing, i also have a n9 64gb from Switzerland, same product code as yours. I must say there's no need to change the product code, you just flash it manually with the desired firmware. You can find step by step guide in this thread, it's fairly easy to do it.

If you (for some reason) want to change the product code you can do it with NSS (Nemesis Service Suite), google for download link, after you download it install the first option (USB something), connect your n9 [sync and connect], open NSS, scan for a new device, select "phone info" and then click "read" and you'll be able to see what's your product code. Now you must change the power mode to local and your phone will reboot in local mode, click enable the product code and write a new product code in the field and press "write". That's about it, set power mode to normal again and press "read" to see if it worked.

I'm not in any way responsible if you harm your device. Do it at your own risk!