Get the cheapest fare you can get out of your local airport to where-ever. Go there, do this, go home. If you make it through, just don't get on the flight.
Be nice to the airline though, they're not a fault (in this issue, at least). Get there early, let them know (afterwards) that you're not flying. Don't trouble them with a refund. Keep in mind that you're probably violating the T&Cs by not intending to get on the flight.
there's a real risk if you do this that you'll end up on the no fly. at least take a flight someplace, earn some miles and come back. Otherwise you may be seen to be performing surveillance, and that can land you in hot water.
That's tricky because there's a big possibility you won't even go through the backscatter. So anyone wanting to do this is not guaranteed to get their chance. Unless you have a printer toner cartridge with you. Fight on.
Be nice to the airline though, they're not a fault (in this issue, at least). Get there early, let them know (afterwards) that you're not flying. Don't trouble them with a refund. Keep in mind that you're probably violating the T&Cs by not intending to get on the flight.