AND WAIT, THERE'S MORE: Remember the good old days when Van Halen insisted that promoters supply the band's backstage dressing room with a mound of M&M's--but with all the brown ones removed? Now the Beastie Boys have raised the ante considerably. The rap-brats (who were scheduled to appear at the Hollywood Palladium Saturday night) have a contract rider that calls for pretzels, beer, tequila, Jack Daniels, chocolate milk and a "rainbow assortment" of condoms to be placed in the group's dressing room before each show. . . . And guess who's a closet Lynyrd Skynyrd fan? None other than Hank Williams Jr., who includes a pair of Skynyrd rockers--"Sweet Home Alabama" and "Working for MCA"--on his new "Hank 'Live' " album. The only thing Hank needs now is a Skynyrd songbook, since on the album, he only manages to remember one verse from each tune--and perhaps in deference to his current label, Warner Bros., he changes the lyrics "working for MCA" to "if you play down Memphis way."