One of my cats, Gus'sers, hasn't been to the vet but one time in years for this very reason. That one time resulted in such significant bites to the vet that the vet was MIA for 20 minutes cleaning up. I don't think people understand the magnitude of terror/fear involved with this type of cat unless they have one themselves.

I was able to get Gus'sers into the carrier by 'trick'. We have a cat hole in the door leading to the basement steps, and I stood on the closed side, with the carrier flat up against the hole. J then chased the cat into the carrier. OK, what then. As the trip to the vet was so God awful I would never do it again. Gus'sers literally climbed the walls, thrashed about, I was asked to leave the room, bit the vet and all the while he couldn't be examined anyhow.

If this vet won't do a sedative, find one that will. There isn't, IMO, any other way.