nosam:
Reflashing the device is relatively simple. You need to install Nokia Internet Tablet Software Update Wizard and follow the prompts. The device connects to your computer with internet via USB so no wifi required.

If you don't have wifi, then you will have to manually download everything needed in the guide on your desktop computer, then transfer the files to your Nokia via the USB cable.

You don't need a BT keyboard to follow the above guide. The first time I hacked my Nokia, I used my stylus. Took about 3 times longer but it still worked.