I am not 100% sure about the Nismo, but the wiring harness in the dash should be the same for each model regardless of which A/V head you have. It would make sense from a manufacturing point of view. It is easy enough to disassemble and check.... all the wires you need are in the back of the A/V Head under your cubby hole.
All info below taken from this thread:
Nav/Dvd hack for 2010
The VSS is pin 82, beside it to the right in bright orange is Pin 81 for reverse signal, and then in green to the right is Pin 80 for Ignition power. Pin 65 below them is your ebrake to ground out so you can watch DVD's while moving.
