How did they get aboard an O'Neil cylinder station? They were in the Wide Roaming Lands and down, down, down water features until they hit the outer sea of the Nested isles.
Okay, so, when you say, Mulder, you don't mean-- Oh, you do mean Mulder and Scully, and she's there too, on this O'Neil station? Why? Hmm...OK, I guess.