How can I get a semi-feral cat crate trained?

You might ask the vet about it. I suggest a closed box crate, not an open wire one. We used to wrap our cat up in a towel, and he loved it.

Maybe you can try to start feeding her close to the crate, and slowly move the food into it each day?

@YARNLADY has a good suggestion. Don’t give the cat a lot of time to think about the fact that she’s getting picked up and put into a box. The towel (cover her head to make her less fearful) can be really helpful. Also a top loading crate will save a lot of hassle for you and the vet. They’re cheap at Walmart.
Please do alert the vet staff that your cat is not tame. Even though the staff prepares for stressed behavior, truly feral fight or flight can be a nasty surprise for them.

You might ask your vet for a tranquilizer.

If there is an organized group in your locality which cares for feral cats and practices TNR (Trap Neuter Return) you could give them a call since they take feral cats in for neutering on a regular basis.

Alley Cat Allies is one such group with many locations. They have a step by step instructions on their website

But if there isn’t one in your location, there may be a group doing similar going by a different name.

As well as giving you tips when you call, they may be willing to loan you one of their specialized transport cages if you offer a deposit.

This would save the expense of buying one for this one-time use Plus, they’re designed differently from regular carriers for tamer cats.

www.alleycat.org