Alternately, he supplies the pinouts so that you could add pins to the 20 pin Nissan connector that you have. If you're like me and don't have ready access to the right sort of pins, you could buy another connector and scavenge them.
I admit that I haven't done my install yet. I just got the last piece (parking brake bypass) on Monday, and I haven't had time to solder the harnesses together yet. I hope that I don't injure my back trying to run the BT mike and GPS antenna. ;-)