NOBODY GETS a party started like a porn star. Calvin Klein, Lou Reed, John Waters, Barry Levinson, Ben Stiller, Christine Taylor, Darren Aronofsky, Rachel Weisz and "This Old House" fix-it man Bob Vila sized up Timothy Greenfield-Sanders' giant portraits of adult entertainers at the opening of his "XXX" show at the Mary Boone Gallery on Saturday. Also there - fully dressed - were the photographer's subjects, including Gina Lynn, Nina Hartley, Tera Patrick, Savanna Samson and Chad Hunt. Afterward, everyone headed over to the Rivington Hotel's penthouse...