Gregory Hines may be a master on the dance floor, but it took him a little time to master the military's fancy footwork in Renaissance Man. Playing a drill sergeant in Penny Marshall's comedy, Hines had to lead a troop of soldiers (including Marky Mark and Kadeem Hardison) through a real-life graduation scene at South Carolina's Fort Jackson. ''It's not easy marching 60 people from here to there,'' says Hines. ''They've got to be on the right step, they've got to do all these maneuvers. I was marching them into hedges and the sides of buildings.'' But with time, the man who hoofed through The Cotton Club and White Nights ''got a sense of the choreography. Once I got that, we were doing double to the rear with a slight hesitation. I mean, we were chain-steppin'. It was great.''