I wouldn't worry about the scent. My snakes shared a room with ferrets before my crew outgrew that room and I had a dedicated snake room.
If the snake can be locked in a separate room while you're away or sleeping I think you should be fine. I wouldn't let the cat in the room with the snake unattended though. My cats will occasionally take a quick peek and sniff in the snake room when I first open the door, but the enclosures are all closed and I don't let them more than a few inches in. Then they're locked out while I'm in there.
So I'm definitely not saying you can't keep both without issue, but it's always best to play it safe. If you can keep them seperated while you're sleeping and away you shouldn't have any problems.