Note that the one time I went to Petco/Petsmart where they give low cost vaccinations, the vet didn't even take the cat out of the carrier in a lot of instances; the vet simply shot the cat through the holes in the carrier. That is not as mean/weird as it sounds; it is the same way sedatives are given to feral cats prior to spay/neutering them.
On the other hand, if you're wondering how to trap him to take him in to a clinic/vet, then let us know; we have lots of people with lots of ideas.
(You can start by feeding him the same time every day so he gets use to food; they withhold food for two days; they put food in trap and hope hunger wins out.)