[rashkae]

Sideload and install the 4.30 firmware. Replace your .Kobo/KoboReader.sqlite file with the one attached, (Unzip the file first.). Eject the Kobo and power off / Reboot. No regsitration, no forced updates, sideload to your heart's content. I suggest also making a backup copy of the dictionaries in your .kobo/dict folder.

Edit: I was mistaken... kind of... If connected to Wifi, the Kobo will still try to download the update on Sync. So you're back to forgetting the wifi networks regardless. But if starting from a fresh factory reset, this method will still get you there without having to do an upgrade/downgrade.