The best way to 'tame' a feral cat is to let them do it themselves. Being by one's self in a room is lonely and boring. My special technique for doing this is to slowly increase the time I spend in their company a little at a time. The first three to five days, I go in, give food and water (two to four times a day, depending on temperature of the room), make a point of looking for and speaking to the cat and then leave. Over time, I start staying in the room on a chair or a bed reading aloud, talking; just being with them: and increase the time five minutes at a time. I provide catnip toys, places to sleep, things to do. I do not touch the cat until they come to me and ask me to do so. First they stay under the bed and I put their food right at the edge of the bed and slowly move it toward the center of the room as they get bolder and bolder. Next, I will bring in a cat fishing pole and tease them with the cat lure. It usually does not take long for them to become acclimated to my presence in the room. About a month into the process, I take them to the vet and get them screened for disease and usually by another month they are out of their quarantine room and part of my pride. The worst feral I tamed took three months; the shortest, three weeks.
I am serious. If I can afford the gas to come get her, I will take her. I am in central PA. She does not have to even be tame. Let me know.
One point. Cats purr as a self-soothing measure when they are severely stressed; not just when they are happy and relaxed. Kind of like a child rocking themselves for comfort? I once rescued a cat that had been mortally run over by a car and the cat purred in my arms all the way to the vet and right up to the moment it took it's last breath via euthanasia. Purrs do not always mean all is well. Extremely stressed cats will also purr right up to the moment they hiss, yowl and attack!