It looks like the vss signal is pin 66 on your PCM color is white/orange. Injector signal for cylinder #1 is pcm pin 13, color is white/dark blue. Don't cut the wires, just strip an area about a half inch long and wrap the wire going to the guino around the stripped area, solder the connection and wrap with electrical tape. I assume you will be able to find a 12v supply that is hot all the time and a good ground.
Go to the wiki:
http://ecomodder.com/wiki/index.php/MPGuino for setup and calibration directions. Good luck.