CAVIAR COWBOYS: Talk about your musical roller...

CAVIAR COWBOYS: Talk about your musical roller coasters. Country star Roger Miller will go from black ties to mud flaps as he headlines a champagne-set fund-raiser Thursday at the Orange County Performing Arts Center (E1), then heads to the suds crowd at the “Great Temecula Tractor Race” on Oct. 6. . . . Country newcomer Hal Ketchum will also amble across the culture canyon. He plays tonight for $5 a head at an Anaheim bar called the Cowboy Boogie Co., then joins Miller on Thursday, where folks in black ties and gowns will be paying up to $500 each.