That poor kitty!
If they knew the cat hated kennels so much why on EARTH would they wait until they had to leave to try anything?
2 hours of being cahsed and fighting will only make this cat's issues worse, and every time they try to put him in a kennel it'll get worse and worse and worse until it's not possible at all anymore, or someone (or the kitty) gets hurt.
Art, pass this on to your relatives for me, ok? They need to look into desentisizing the cat to the kennel - with the difficulty level as you've described this will likely take a year to completely fix.
1) Take the door off the kennel and leave the kennel out in a room they use often (living room, etc) with a comfy towel in it. Every day put yummy treats in the kennel twice, otherwise completely ignore it.
Once the kitty is obviously eating the treats, move to step 2.
2) Start feeding the cat him meals in the kennel.
Once he will willingly enter the kennel with a human nearby move to step 3.
Steps 1 and two will probably take a few months, 3-4 I'd guess. So they need to keep at it and be patient!
3) Put the door back on the kennel. Keep feeding him in there, and putting treats in. When he enters the kennel to get the treats close the door gently behind him. As soon as he's done eating open the door so he can leave.
4) Extend the time between when he finishes the food/treats and when the door opens gradually.
5) Once he's fine in the kennel with the door shut they need to practice moving the kennel next. Get him in and shut the door, lift the kennel to standing height, then gently set it right back down. Gradually start adding in steps, then going outside to the car, etc.
If they work at it they could have him happily loading up in one minute within a year. Much safer for everyone involved, and no stress for the kitty.