Milk or chicken. Just put them in the room. Water too, and whatever cat food. Litter box.
Don't touch it unless it comes to you. Cats don't like you touching their face or head, but they like touching your hand with their face or head. Does that make sense? If it gets to the point to let you touch it, offer your hand, but let it decide what to do.
Also, when it gets out of the room: if you start walking towards it, and it gets scared or stiff, and starts walking the way you want to go, just turn around. It'll think you're chasing it otherwise.
I have a cat who was abused at his former home, and after 2-3 years is still terrified of us touching his face, or that we're going to step on him. However, he loves to rub his face against our hands.
Cats are weird.