There is no easy answer to this as all cats hate change and this is not natural to them. You need to give him more fuss and qyuality time as he probably feels he is being penalised. He doesn't understand that it is for his own long term good. I have experienced this with my cats and, particularly, Beanie who had to wear a collar for in excess of 1 year.
There are 2 possibilities to make life easier:
1. Many of the collars are crudelty made but there are collars available with padded trim around the narrow part which fits around the neck. Th very expensive.ese are
2. An alternative but more costly solution is to buy a 'Bite Not' collar. These are made primarily for dogs but increasingly being used for cats. They can be expensive and we paid around £30 but we needed it for longer term use. They fit around the neck leaving the head free but restrict head movement.
The link below is simply intended to let you see what they look for.
http://www.bitenot.com/