You won't find any good solution by now. Most VST's don't even use the same pulse/triangle/noise waves as the good old NES did. As far as I know the pulse channels have a really interesting algorithm though they nearly sound as "normal" pulse waves you can generate on a simple synthesizer. But I'm not sure, however if your sound does not have to be 100% NES you can "cheat" with synths including a pulse gen. Triangle however is very tricky, it seems to use a special Pitch Envelope or something, I don't know. For the noise channel you should use blue noise generators.
I haven't seen any Reason Refills by now but I'll tell you if there exist some.
Another solution (which I prefer) is creating a NSF file with a long played note off a sound channel (I made them 1 min long), rip the track to WAV, and load it into your hosts' sampler. All you need is a good sampler. I use Fruity Loops along with Halion 3. Cubase already comes with Halion 1 so consider yourself lucky. Too bad this sampler isn't capable of "volume stepping" like the NES and uses only normal DCA Envelope.
Sorry for my sucky english which sucks.