I'd bet there is a wire or 2 involved in the printer signaling. Haven't looked but I'd bet it either "pulls up or down" when the eye sees/doesn't the paper. Cut it? Now what. It doesn't work anymore anyway - so whats to loose? Bet there is a second wire/connection to the paper out as well.
I also bet somewhere is a LPT signal drawing that might show which pin on the port gets in the signaling process -- you could pull the pin from that one -- but then you'd have a bad cable too.
(Seems like a lot of bets -- but I'll cover them... 2cents apiece)
Look forward to seeing the pictures/sketches -- sounds like an interesting project. Any links or other info would be appreciated too.