Candidate elimination help

Hey folks, happy puzzling! Best of luck if you're doing round 2 today. I submitted mine yesterday, and did as the Rules section implied: "it is expected that participants will print and solve on paper." It would be nice for candidate elimination notation, but I'm assuming using something like Sven's Sudoku Pad is expressly disallowed?

If so, I'm curious what others have found useful in terms of candidate elimination markings on pen and paper.

Cheers,
sudorkus