If he was abused, or even feral, he's going to need a lot of time and patience. Some people suggest leaving a tv or radio on for him to always hear something soothing, like classical music. Perhaps if you just spent time in the room, reading, watching tv, doing paperwork, talking on the phone, etc and not purely in there to fuss with them, they'd become accustomed to you sooner. They'd definately watch and learn your natural movements and will feel safer in your presence.

If the blackie was ever "punished" for eating (either by a human or another animal) he's going to feel scared to eat. Can you put the food and litterbox in his dark space? He'll be much more cofortable eating in there. Then s-l-o-w-l-y move his dish away from his dark space and into the open. I'm talking an inch or so a day or every other day! Change of any kind can throw a cat through a loop. The litterbox can be something as small as a baking sheet (those aluminum foil ones are great for this) so that it fits under a bed or on the floor of a small closet. Provide a soft spot for him to sleep in his dark spot. Offer him toys (like catnip) and a soft stuffed animal. Believe it or not, some cats DO take to a stuffed animal for comfort.