Making good on his promise -- announced at a press conference last week -- magician David Blaine, 27, was sealed inside a six-ton block of ice on the ground floor of the ABC Studios in New York's Times Square yesterday at 9 a.m. He is due to remain there for some 58 hours, or until tomorrow night -- for a primetime ABC special. Blaine, shirtless but wearing a protective gel and cargo pants, will not sleep, he said, because if he did he could risk his skin's sticking to the ice, which was specially sculpted to fit the contour of his body -- as well as outfitted with an air tube. To prevent frostbite and other maladies associated with the cold, he has been on blood thinners. He also was fitted with a catheter and has not eaten since Thanksgiving dinner. In addition to a large crowd of admirers and reporters, Blaine, infused with the spirit of his idol Harry Houdini, was accompanied yesterday by his girlfriend, model Josie Moran, and his younger brother Michael. "They want to make sure I don't die," an already red-eyed Blaine told The New York Times.