Just to be safe in regards to leaks, why not pick up that plumbers vinyl tape and use it? Erm.. what I'm talking about is a roll of thin, white (usually), vinyl that you wrap around the threads before you screw the "nut" onto the "bolt" (lezlie and compression in this case -- I think??). Wrap it around whatever you're screwing into the pass-through, so that's compression on one side and something on the other.