I've lost one of my keys for my 350Z and now have the replacement cut but I cannot figure out how to add it to the programmed keys in memory. I figured out how to add the new key fob but the new key itself is leaving me at a loss.

You have to take it to the dealer and have them program it for you. Probably cost you about $50

As far as I know this is the only way even though you can program the keyless remote without the use of a scanner.

Has to be done with the Consult II scanner

There are aftermarket programmers that will do this. Many locksmith have this equipment (auto specialists).

You don't have to go to the dealership for keys!

http://www.hightechcarkeys.com