I have fully tamed ONE feral kitten, and she was started. So Hissy has TONS more experience than I do. However, my little Blue is like a miracle girl, so I am going to let you know how I did it. This is the link I based my care on:http://www.cat77.org.uk/articles/feral3.htm
My litter was trapped at 5 weeks, and I do not know how they were treated. I was told they came from a hoarder. Then they stayed at the vets office for over a week being handled and medicated. Then I got the two tamest kittens. By the time I got them at 10 weeks, they were scared, but would tolerate being held by humans and petted. Red shook as you held her, but Blue didn't. Neither tried to get away. They were not pets at all, just kittens who learned to allow "forced" petting.
I kept them in a cage at first, in a separate bedroom/playroom. These little animals are like wild baby deer...I think it would be terrifying to be in a high traffic area! Yet they do need to see us. They also must be kept from your cats until they are vetted and have vaccinations. (Not a problem with mine, they were old enough to have shots already.)
Disclaimer-I have 3 kids and an akita. The high traffic areas of my house can be chaotic. The playroom has video games, so the kids go in often, and we can play music CDs when we are gone. The kids are good at being near the animals without pestering them. If you have that in your hightraffic area, it would probably be fine. We get a certain amount of yelling and running in our house!
Hissy does not cage. She sets up a separate room with few areas to hide, and no place to sneak away into a crevice.