found this for you
Nitro beers require either a gas blender (mcdantim) with a CO2 and a Nitrogen tank or a premix bottle of blended gas. If this is for a home unit, go with the bottle of pre mix. The regulator for nitrogen is different than CO2, it has a male fitting as opposed to CO2 which has a female fitting. Either an adapter or a new regulator is needed. The faucet for nitrogen is a "creamer" style which is also needed for a proper pour. The faucets can be pretty pricy. www.micromatic.com
is the place for more info and to order parts.
personally I don't know if a nitrous oxide tank and a nitrogen tank are interchangeable.