ON THE TOWN: We bet you're just dying to know how Billy Idol will open his shows here later this week (Friday at the Forum, Saturday at Irvine Meadows). As his band breaks into Idol's old hit, "Dancing With Myself," the rocker makes his entrance by running between a pair of huge wooden women's legs, which are adorned with seamed stockings. Asked why the props were built, Idol explained: "They're there to keep me from getting lonely on tour." If you're looking for a raucous show, Idol's concert may be the ticket. At a recent show in Wooster, Mass., Idol paid tribute to rock icon Jim Morrison by dropping his pants during an encore performance of the Doors' "L.A. Woman." So far, celebrity visitors have included Jack Nicholson, who came to an Idol concert in Troy, N.Y.--and left early. . . . Closer to home, veteran club booker Jan Ballard is back handling shows at the Music Machine after a two-year stint at Raji's. Ballard promises a series of upcoming theme programs, beginning with the debut this Thursday of the First Annual Bad Girl Wrestling Championship. The show will feature a trio of all-girl bands--Super Heroines, Bulimia Banquet and L-7--who will both perform live music sets and participate in wrestling matches with guest stars Tequila Mockingbird, Gwen (formerly of the Pandoras) and several members of the Lame Flames.