Please bear in mind that I'm a dog-person, not a cat-person, so I'm giving an adapted version of the advice I'd give for dogs!
Could you try putting the collar on him and then dishing out some tuna (or something else that he goes mad for, or even just meal times if he's a food-loving cat?) The food might distract him from the collar for a couple of minutes. Obviously if he's ignoring the food completely, just take it off (maybe try leaving it near his food bowl so he gets to see it) but if it works and he puts up with it in favor of eating the fish, leave it on until he's finished and then take it off before he has chance to freak out about it!
It would work on a particularly distressed puppy, and since it's a behavioural trick and not a species-specific one it could work in this case too (depending on how much he likes his food!!)