I donno about NX2k, but if the horn system is anything like the B13 SE-R then yes it will work. Your real problem is to make sure you disable your airbag system first, there are some crap u gotta pull out before u pull the stock wheel off or else the airbag will go off on you. As for the Steering wheel (I do have a momo on my se-r)... I assume you already got an adaptor hub? The way the nissan horn work is this, the horn system uses one wire as the positive end, the ground/feedback/negative end is actually the hub itself. Your adaptor hub is of course made out of medal so all you ahve to do is connect the one wire for the horn to the connector on the momo thing, and find something to connect the other end of the momo center thing to the hub. I used a paper clip and it works flawlessly
P.S. make sure you greese the contact area first, and make sure you insert those "pins" onto the hub before u put it on, medal pins should come with the hub which is necessary for the automatic "click back" thing for the signal lights to work.