It seems like it should be a fairly simple modification (thinking about it, anyway, not actually getting to all the wires). If you think about it, all the wires (excluding the ones to the driver's window) go through that switch. The driver's side switch has one wire coming in from an ignition-switched positive source (may be negative, but I doubt it) and the other goes to the window motor. The other switches (on the driver's door and all the rest of the doors) must have one wire running from the ignition (quite possibly branched off of the same wire that runs to the driver's switch) to the lock-out switch, and then to the switches and on to the motors. Therefore, you could, most likely, remove the leads from the lock-out that go to the driver's panel and wire them directly to the wire that is always on with the ignition. I'd try and draw up a diagram if I had a place to post it. Anyway, that's how it seems it should be. However, knowing Nissan it's probably run through a gazillion relay and other switches before finally performing its function.
However, if you don't plan on ever using the switches on the passenger doors you could always just unplug the wiring harnesses from the switches you don't want anyone to use. However, this will mean that you can only operate those windows from the driver's door (assuming the switches aren't wired up all funky and the driver's switches rely on the other switches).