ON THE TOWN: Guy Kemp isn't the only deejay who will do just about anything for some attention. Take KLOS-FM morning wackos Mark Thompson and Brian Phelps, please. To help celebrate Valentine's Day, the loony duo is going up in a crane, which will dunk them in a vat of chocolate. The event takes place between 7 and 8 a.m. Friday at the KLOS parking lot--listeners are invited to stop by and bombard the chocolate jocks with chopped nuts and sprinkles. . . . Meanwhile, congrats to KROQ program director Rick Carroll, who was nominated by the Gavin Report for rock radio programmer of the year, while KROQ won a nomination as one of five stations up for best album-rock outlet. . . . And it was heavy-metal heaven at the Forum the other night when everyone who'd ever worn a pair of Spandex tights was on hand to pay homage to newly revived rockers Aerosmith. That everyone included Motley Crue's Nikki Sixx with W.A.S.P's Blackie Lawless (what a pair!), Tommy Lee (with Heather Locklear), Jon Bon Jovi (who hopped on stage and sang "I'm Down"), Bangles Vicki Peterson and Michael Steele (those gals are everywhere!), plus members of Ratt, the Cult, Metallica, Guns N' Roses, Faster Pussycat, Gene Loves Jezebel and Black & Blue.