Off the top of my head a person would need

1) Tank
2) regulator
3) A beverage tap. A cheap one aimed at dispensing wine should be fine.
4) A length of hose and some clamps.

I think that's it.

Beverage grade is pretty pure. Oxygen will cause problems for beer and wine the same way it would for photographic chemicals. I think the problems with lower grades are things other then Oxygen. Wouldn't oxygen be less of a problem with medical grade nitrogen? I can't find anything describing beverage grade nitrogen. Well nothing more then calling it pure. I did find medical grade and it does include a very small amount of oxygen. 8ppm