Fill a two litre bottle with water and freeze it with the cap OFF. After it is frozen cap it and wrap it in a towel. This will give the kitty a cool spot to lay against. It can also be placed on top of the crate and it will cool the insides.
You can lay a wet towel down and sprinkle it with catnip to entice him to lay on it.
Put some water in the bathtub just enough to wet his paws and put his food bowl in the tub with some nice canned food to tempt him to go in and eat, or float toys in the tub to see if he will chase them.
Put a bowl of ice or block of ice in front of your fan to direct cooler water at him
Make sure he has cool water to drink and float some ice cubes in the water as well.