I would test the starter circuit before testing the starter.
test that the starter is getting a 12 volt.
unplug the 12 volt start solenoid wire, while someone is turning the key to start, check to see that you are getting 12volt on that circuit.
if you don't have 12volt, its a wiring problem on the start solenoid circuit problem.
if both those tests are good, jump your starter manually by putting a 12 volt to the starter solenoid with the car on, this should get the starter to turn over.
if it does not turn over, its a starter problem, if it does, you can rule out the starter and starter circuit.
if you know how to do it, you can pull off the front dash and test the contacts on the ignition switch to make sure it is working.
if you cant figure it out, take it to your local nsx mechanic, we can only do so much over the internet.
keep us posted with your progress