OK, to put all controvery aside, it works! Its a simple matter of cutting the gray/silver striped wire to pin #28. This not only allowed me to enter a new destination as I drove, but I could also access all of my cellphone options while driving. The only downside I could find was that as long as I had the speed sensor signal interupted, the NAV showed my car at the same location where I first threw the switch, so you only want to interupt the signal long enough to make the changes you need, and then reconnect the signal to let the NAV update your location. One VERY important note if you are going to attempt this: ignore the pin numbers molded onto the A/V plug. Not only does Nissan totally ignore those numbers, they assigned the new pin numbers BACKWARDS from the order shown on the plug, and with all odd pins on the top row and even numbers on the bottom, as shown on the datasheet from the manual above. The pin numbers above are looking at the back of the connector, with the wires sticking out toward you. The Gray/Silver striped wire you want to cut is the 4th wire from the left on the bottom row. Simply connect it to any SPST toggle switch, to open the connection when you want to access the grayed-out menus. I had this toggle switch in my junk box, so I dremeled out one of the extra switch blanks in the dash, and trimmed it in nicely with an Xacto knife.
While I was at it, I decided to also try out my Prius "Anytime Backup Camera" mod, which also works perfect. You need to cut the Green/Silver reverse wire to pin #30, install a simple 1N400x series diode in series with the cut, with the banded cathode side toward the NAV. Then, I supplied +12 volts to pin #30 through my toggle switch, which I got from pin #31, a Purple/Silver wire, which forces the backup camera on at any time. In my Prius I used this to connect a Garmin GVN52 navigation unit to the display, since I didn't feel like spending the $3000 upgrade to get NAV in 2006. I have also used the video input to play movies while parked, but I don't know if I'll go to that extra trouble in the LEAF. I guess it could be useful if I was sitting for a few hours charging somewhere, but that's about all I can think of. I always wanted to install a large IR array out front on my Prius, and a camera, to see through the fog better, but never got around to it.
A couple notes on removal of the NAV, and running the wires:
1) The complete trim assembly around the NAV simply pops off, and then you lift up slightly to release a couple fingers in the dash. You need to unplug the emergency flasher switch to be able to lay it down out of the way.
2) The NAV itself is simply held in by 4 large Philips screws. remove them, pull it out, and unplug the large 40-pin plug on the driver's side.
3) To run the wires I dropped the panel above the driver's feet. It is held in by 2 plastic Philips screws, which only need 1-2 turns to release, and a large plastic nut on a stud on the firewall. This allowed me to grab the wires I fed in from the switch, and get them over closer to the NAV.
4) I stuck a small pole down a hole to the left of the NAV, which came out right above the accelerator pedal, so I could tape the wires to it and pull them up.
I don't think Daryll will mind, I hacked this picture off his site to show how the Anytime Backup Mod works:
The diode keeps the backup lights from coming on whenever you throw the switch.