If you've only had them for 4 weeks, they are still a bit scared of you. They may never become lap chickens, but they will learn to trust you and come to you. The best thing to do is to walk slowly around them—the faster you move, the faster they'll move (to get away)! Also, be predictable. Doing routine things become familiar to them, and they'll learn to anticipate what you're doing. Try not to startle them, like dropping something close to them. Startling them can undo days or weeks of trust-building. As they become more comfortable with you, you can try sitting with them and giving them treats, like sunflower seeds. Try sunflower seeds without the husks, as these are irresistible. First put some on the ground near you and sit still while they come to eat. After a few days you can try getting them to eat out of your hand. After that, try holding some on your lap, and the bravest ones will jump onto your lap. Don't try to touch them at this point. Keep building the trust, and once they'll stay sitting on your lap after the sunflower seeds have been eaten, then you know you've made friends with them. Probably they'll jump off if you try to touch them, but you might get lucky and find one or two that like to be pet. A word of caution, once they are on your lap they will try to peck at the whites of your eyes or your teeth if you're smiling. It's not that they are attacking you or anything, I think the shiny white is appealing to them. So keep your face out of pecking range!
I did exactly this with one of my skittish flocks, and now several will jump on my lap as soon as I sit down. Also, I always put the sunflower seeds in a purple drawstring pouch. As soon as they see that pouch they come running over and they fight for pole position on my lap!
Good luck!