I routinely brush and scale Chagall's teeth, and he's pretty good about it, but Gretta is
amazing!! I start my dogs off on an oral care program as puppies, so they come to tolerant it rather well. I think to start doing it on an older dog, you'd need to proceed
very slowly.
If the dog is already used to having its teeth brushed, it might be a bit easier. If not, you can start off by using dog toothpaste on sterile gauze to rub its gums and, after gaining some acceptance with that, move on to a toothbrush or finger brush if you like. Then take the plunge and try using a scaler, maybe one or two teeth per session, and build up to doing the whole mouth.
Handling the scaling tool is a bit tricky, IMO. You don't want to pierce the dog's gums unnecessarily and you have to resist using too much pressure. Make sure to "sterilize" the scaler after use. Good instructional video, good dog, and good luck to anyone attempting this! The good doggy breath, teeth and health are worth it!!