Frontline for cats has been used successfully to treat chickens for mites. Draw it up into a syringe with a small needle and put a few drops on the skin on the back of the neck of each bird. Presumably it gets distributed into the skin glands just like it does in cats, and kills the mites when mites bite. It lasts for a month on a cat, but is thought to last longer, maybe up to 3 months on chickens. Clean out the coop and spread fresh, dry litter, keep the coop clean and dry. You don't need to do anything else to the coop. As the mites bite the chickens, they die. Eventually mite population in your coop dies out.
Because Frontline works in the skin, and is thought not to get into bloodstream, there is no need to stop eating the eggs. However, no one has really studied this in chickens, so to be on safe side, I use Frontline around molting time, when chickens are not laying many eggs anyway.