* * ANTHRAX. "I'm the Man." Megaforce/Island. Anthrax's 1987 LP "Among the Living" is approaching classic status on the speed-metal underground, but "I'm the Man" only fitfully delivers on that promise. Of course, as a six-song EP with three versions of the rap-metal hybrid title song, it's not really meant as a follow-up. It's merely a stop-gap and a thank-you to its militantly faithful fans, who will no doubt flip over the live versions of concert faves "Caught in a Mosh" and "I Am the Law" and a studio version of Black Sabbath's "Sabbath Bloody Sabbath." But for those not already converted, "Man" is a poor introduction to this New York quintet. With their often progressive politics, witty, perceptive lyrics and musical chops, Anthrax could have come up with something really special when it decided to fuse metal and rap. But the three versions of "I'm the Man" are merely rather juvenile, sub-Beastie pastiches.