"Inhalants" is not classed in the same way "disassociatives" is, to my thinking. The former encompasses things like keyboard duster, gasoline, and freon, and the latter is typically associated with NMDA antagonism, though not always. What do you mean?Honestly, I feel nitrous has more in common with other inhalants than it does with other diissociatives...
I think what you want is a nitrous tank and an oxygen tank, and two hoses. I've heard of people hooking up a supply dentist style (probably shouldn't be attempted without an O2 tank to supplement) and just sitting around for an hour breathing a nitrous and oxygen mix. You've gotta find a tank first, though. I'm not sure how healthy it is ...