While this might not be the answer you guys are looking for, putting back the decryption keys to the C-board with the ArcadeHacker method is really easy. You need an Arduino and a LCD shield. I just did it to a King of Dragons board and from start to finish it took like half an hour. You need four wires for key writing, one wire for +5V and one wire for GND.
http://arcadehacker.blogspot.com/2015/09/project-update.html
Put a good quality coin cell in and it's good for another 20 years (or more, the original battery on my board lasted almost 30).
http://arcadehacker.blogspot.com/2015/09/project-update.html
Put a good quality coin cell in and it's good for another 20 years (or more, the original battery on my board lasted almost 30).