Please, don't. Pee on your own lap.
Anyway, Set was pretty cool, and I don't think the Vault Dweller's Memoirs in the FO2 manual specifically mention which Necropolis ending was canon, but don't expect him to return. He wouldn't be as cool. Unless we get Jim Cummings back! Damnit, that guy did some amazing voice acting. They better get ahold of him for New Vegas.
They should get hold of everyone from the original that will agree, for voices in New Vegas. [ except the late Tony Jay
]
*And again, as I put to Emil three times before... If Ron Perlman is called back into the studio for any reason, please have him record the last line from Fallout 1 about Junktown's intended ending... Once it exists... have it on the game DVD, and let the modders work with it.