When I bought my R33 it only came with one key, I went to local Nissan dealer who has FAST software.
He looked it up and said you cant get actual Skyline 'S' one anymore, they just have a Nissan one (same key as N15 Pulsar I think he said). I ordered it ($15 or so), was just a silver key with black top with Nissan written on it, then went to locksmiths and got it cut for $5.
AFAIK can only get this or a GTR key.