Our kitten became Feral and we can't pick him up to take him to the vet.

Our one year old male cat that was born to our office cat was born Feral.  He always hid when we wanted to play.  When it became time to take the other kittens to the vet and find homes for them we could not catch him.  He is still at our office, we take care of him.  I would like to take him to the vet to get his shots and have him neutered.  Do you have any suggestions on how we can do this?  I can't get him near a cage, he saw me take away his mom and sister in one and won't come near it.

Tackle him. Or set a trap... What i do (not with cats but with other animals i have needed to catch). I set up a a food bowl and i get a box with a stick lifting it at one end, the cat walks under to eat the food and you will be hiding with a string attached to the stick holding it upright then when he's completely under pull the string and get there as fast as you can and hold the box down, speak to him lovingly and let him know it is okay, you will then have to get him out of the box, i would slide a board under it then carefully put it upside down slowly so he isn't uncomfortable and he cant get upright by himself then your done! 

An easier way would be to get him out with treats etc but if he as skittish as he sounds he might not go for it...

A humane trap may work. Tie the trap open and feed him inside it for a week or two. He will get used to eating in the trap. The night before your app't, set the trap. He'll be upset but he needs to be neutered. You can put pee pads under the trap in case he soils himself when trapped. As soon as the trap springs, cover it with a blanket or towel. This will calm him down. He can stay overnight in the trap without a problem.

When you take him to the vet's take a carrier so the vet can put him in that after surgery. Does he stay inside or is he an inside/outside cat? He will need a quiet place to recuperate from the surgery - boys only need a day or two.

There are also drop traps, similar to the box described by MeganandAlbert. They are expensive but your local rescue may have one to lend you.

I agree with Ondine:  either a human trap (havaheart) or drop trap.  Both may be available from your local humane socieity/rescue group.  He does need to be neutered and vaccinated.

Where do you live?