Start out by keeping them where they can see and hear you if possible - a play pen in the living room or next to you gardening, for example. Try to say their names or "chicky chick" or whatever you want them to answer to before you feed them, so they learn that call means food. Hand feed them treats. Try to give off a calm feeling around them, avoiding sudden movements, especially from above them.
I also recommend having a tame pullet with you sometimes as well, so they can see you being nice to her and her enjoying it. That is one of the big things that helps feral or abused dogs recover - they see another dog trusting you and realize you're a "safe" person. I'd think it likely that chickens, as similarly social creatures, would be able to learn the same lesson.
They may never be "lap chickens," but I definitely think you can build trust. Chickens can recognize individuals, so they can learn that you are a nice human.
