I've worked with feral puppies before, as I am involved with a rescue that works on First Nations Reserves. It is time consuming, and requires endless patience.
Have you ever looked into clicker training? That is where I'd go with this. Are the puppies penned up, where they cant run too far? You do NOT want to force these pups... but you dont want them to be able to avoid you either.
Here's where I'd start. I would take out really smelly, wonderful, high value treats, 2/3 times a day. bring a book, and read aloud, while periodically tossing treats out to them. Do not make eye contact, do not reach out to pet them, just sit and read. after 10 minutes, get up and leave (It's best to bring their meals and leave the dishes where you sit when you leave.) Let them get used to your undemanding presence. The pups should start to show some interest in you after some time. Every pup is different, it could take days, or weeks, but once they start showing interest in you, this is when you start clicker training. If you can seperate them for this, it's best, but if you cant then do your best to reward the pup that's doing what you want. Start clicking when a pup turns it's head towards you, toss a the treat right at the pup, when you have the pup looking at you reliably, hold off on the click and see if the pup will take a step towards you, when she/he does, click and throw a jackpot of treats, then wait for another step. throw the treats closer and closer to you.
try to not look the pup in the face, sit half turned away, with your eyes downcast. Is shouldn't take long before the pup is getting right up close. Put sone treats on your knee, or right behind you, or on the ground with your hand a few inches away.
You can use a target stick, and teach the pup to target the stick with his nose (by rubbing a smelly treat on it, or smearing some peanut butter, or tube cheese on the end and clicking then throwing a treat towards the pup.) eventually you can get the pup to target your hand, or some other body part.
An understanding of clicker training is needed here. I would seriously recommend you read the book "Reaching the Animal Mind" by Karen Pryor, or at the very least go to her website
Karen Pryor Clickertraining she has alot of very useful information on her site.
Clicker training is extremely effective in working with feral/shy/aggressive dogs. She even has a video on clicker training wolves. You will not be wasting your time by looking this stuff up