I adopted 3 little spooky boys from a local shelter. They had been transferred to a PetSmart location but never handled so they bolted from humans. With these guys I did the "down the shirt"method. Long sleeve shirt on the bottom, another looser shirt on top. Tuck both into your pants. Put babies down your shirt and ignore them (I usually lay down and watched TV or read as they cautiously moved around). This gives them the comfort of being covered up, and no hands grabbing at them, but they get used to your Snell and movement at the same time. Over time something clicked and they are sweet young boys who love to come out and play
There's all sorts of things you can do. Hand them treats once they are curious enough so they realize you are the bringer of good things, sing to them, etc. Have them out initially covered up as that can help reduce their fear a little. Try not to handle them but kisses if they are close enough is good
Once they get more curious in their cage and approach readily you can initiate play seasons by gently reaching over the top of them,grasp their shoulders give a little shake, and use a high pitched happy voice. They may seem confused at first but if they start to bounce you are well on your way to hand wrestling sessions with happy babies.