I need to treat ringworm in stray cats !

Hi all, A stray cat has brought her kittens to my backyard. I believe they have ringworm. I can't get anywhere close to them without them running away, otherwise I would take them to a no kill shelter. I was wondering if there are any tablets that I can buy online or over the counter to treat them until I can gain their trust. I want a tablet, because then I can crush it into powder and put it in the food I have been putting out for them. Also I need something online or over the counter as I obviously can't take them to the vet since they won't let me anywhere near them. 

Buy Clay powder Diatomaceous Earth Food Grade google for more info. Dirt that's dirt cheap buy at health food store.

I read about this product but wasn't sure if it treated ringworm specifically?

Even if they don't have ringworm they could have other things good reference link;   

http://www.ringworm-treatment.net/diatomaceous-earth-and-ringworm-manage-ringworm-in-pets-naturally/

For people: external fights athletes feet, internal candida any parasites (eat raw fish?)

DE food grade looks like baby powder ask for extra milled finer yet some health food stores may/may not carry.