The fateful day when this movie-mad child got close to his Hollywood dream came in the summer of 1965, when 17-year-old Steven, visiting his cousins in Canoga Park, took the studio tour of Universal Pictures. ''The tram wasn't stopping at the sound stages,'' Steven says. ''So during a bathroom break I snuck away and wandered over there, just watching. I met a man who asked what I was doing, and I told him my story. Instead of calling the guards to throw me off the lot, he talked with me for about an hour. His name was Chuck Silvers, head of the editorial department. He said he'd like to see some of my little films, and so he gave me a pass to get on the lot the next day. I showed him about four of my 8-mm films. He was very impressed. Then he said, 'I don't have the authority to write you any more passes, but good luck to you.' '' The next day a young man wearing a business suit and carrying a briefcase strode past the gate guard, waved and heaved a silent sigh. He had made it! ''It was my father's briefcase,'' Spielberg says. ''There was nothing in it but a sandwich and two candy bars. So every day that summer I went in my suit and hung out with directors and writers and editors and dubbers. I found an office that wasn't being used, and became a squatter. I went to a camera store, bought some plastic name titles and put my name in the building directory: Steven Spielberg, Room 23C.'' Two years later, Spielberg enrolled at California State University, Long Beach, but it is safe to say he matriculated at Universal U. Cramming 15 1/2 units into two frenetic days of classes a week, he was able to spend three days on the studio lot, asking executives to watch his films. ''They were embarrassed when