Reusing steering wheel controls
From what I can gather it looks like its a 2 step process. First you need the loop back connector that goes in place of the stock Nissan blue tooth module that plugs in somewhere on the passenger side of the car like the rear of the trunk under a panel.
That is part PAC BT-SWC-NI1 Its a connector with 2 leads that loops 4 pins.
Then you need the traditional steering wheel control module box PAC SWI-CP2.