I would never do it myself either, but I wouldn't use that method if I did. My vet uses a dremel and even with someone helping him it took a half hour wrestling match.
He's about 10. He won't chew on cuttlebone or calcium block and I'm taking him to get his beak trimmed every 6 months now after a couple of years of not even needed it. There seems to be nothing I can do to keep it at a reasonable length on it's own.
There is something that I don't understand about keeping a beak short. The advice is to feed the tort on something rough like slate or some type of rough rock. How does that really work? I feed my torts on slate and rarely does their beak even touch it. If there is a pile of greens, obviously...