This is a great topic. OP, I understand the concern for the stress involved for a 17 year old cat for questionable benefit. As others have said, I would look for a vet that makes house calls, let them know you have the swelling under control and just want the tooth pulled. And as someone mention, if you have to ask, please don't do the extraction yourself.
To those freaking out about a gunshot as a method of euthenasia, it's the quickest and most humane way to put down an animal (if done correctly, big caveat). It might not be the most humane for you, the owner, but with a distraction like food, the animal doesn't know what's coming, and doesn't feel anything. If I had the stomach for it I'd do that for our old dog when the time came, as she has fainting/seizure episodes and I think the drugged falling asleep will scare her (not to mention her hating the vet, and being really nervous with strangers in the home), but I don't think I could handle the mess/cleanup with all the other existing emotions going on.