The Barnes and Noble on Sixth Avenue and 22nd Street locked its doors around 11 a.m. yesterday, hoping to stem the crush of spectators. Those who couldn't get in crowded around windows, pushing and pulling for hours in the rain, hoping for just a glimpse of the magic within. From the outside it looked like Bill Clinton himself might be signing books, or at the very least, a crew of Playboy bunnies posing for pictures with fans. But the girls that attracted the mob yesterday weren't know for writing books, and they certainly don't pose in bikinis. These girls were the Golden Girls. The bookstore quickly sold all of its 400 copies of the DVD set, and more than a dozen security guards and staffers were needed to keep order as the slow-moving line of fans snaked through the store.