1. Get your serial port working (the pinout is documented in two places on the wiki)
2. Get a running linux system
3. Connect your serial port to the linux system
4. Jumper JP2
5. Ask me for help when, not before, you see "<" (or ">", I forget which) output from the serial port. I will give you a program that you run with an argument of the serial port, which patches your ROM... but I haven't written it yet. If I get bored before you get your serial port working I MIGHT write it then, but I'll get it for you quickly if you actually do that yourself.
6. Keep track of what you do
7. Write a WIKI article on it