The greatest leadoff hitter of all time is beating the bushes, trying to get back to the majors--and still leaving 'em laughing at every stop. Nobody in baseball history has scored more runs, stolen more bases, drawn more walks or provided more entertainment (some of it unintended) for so many teams than Rickey Henley Henderson, the greatest leadoff hitter ever, a superstar so big that his middle and last names became superfluous. The legend of Henderson is real, all right, as real as the check-cashing service with the metal security gates on Broad Street in downtown Newark, which is about all the local color there is in the neighborhood of the mostly empty Bears & Eagles Riverfront Stadium, home to the Newark Bears of the independent Atlantic League--and, at the moment, to Henderson. Henderson signed a minor league deal last year with the Boston Red Sox that included an invitation to spring training and a $350,000 salary if he made the team. After he played his way onto the Boston roster with an impressive spring, Henderson groused that the Red Sox were underpaying him. Interim general manager Mike Port reminded Henderson of the conditions he had agreed to. "Oh, that?" Henderson replied. "I canceled that contract." Says Port, "It was the first and only time I've ever had a player tell me he canceled his contract." Red Sox president Larry Lucchino telephoned San Diego G.M. Kevin Towers, asking how Towers had appeased Henderson during their contract squabbles in the past. A road without gravy is no sort of place for this kind of story to end. And so, at 44, ever independent, the legend goes on. INSET: RICKEY BY THE NUMBERS.