Leo and Liz could use a funny dog -- just as comedy insurance, though, because essentially they're in good shape. "Leo & Liz in Beverly Hills," a new CBS sitcom that begins a six-week trial run at 8:30 tonight on Channel 9, bears a passing resemblance to the hit movie "Down and Out in Beverly Hills," but lacks a hilarious pet to correspond to Mike the dog, true star of the film.

Even so, the comedy, starring Harvey Korman and Valerie Perrine, is possessed of obliging funniness. Derived not from the film but from one of the episodes of "George Burns Comedy Week," an anthology series that had a short run earlier in the season on CBS, "Leo & Liz" is the story of a nouveau riche couple who've moved uptown in a hurry -- from the depths of New Jersey to the heights of Beverly Hills -- and now try feverishly to fit in.

In the premiere, Liz is throwing a party and fears it won't be considered trendy unless an "A-list" celebrity is among the guests. When Leo rushes out to Le Petit Chalet, an overpriced grocery store, for tonic water and limes, he bumps into Liberace, and by accident they end up exchanging driver's licenses.

Does that mean Liberace will show up at the party and rescue it from disaster? I leave that up to you -- and Pamela Pettler, who wrote the slow-to-start, but eventually disarming, first episode. It was directed by comedian Steve Martin, who, with Carl Gottlieb, is executive producer, as they were for the Burns show.

Although there are already too many sitcoms on the air, "Leo & Liz" has a tone of its own, a daffy affability reminiscent of Hollywood screwball comedies. It is not, thankfully, another trendy "sensitive" comedy about a single woman making her way in the modern world. It's good brash farce. The show's version of quintessentially dull party chat is hilarious.

Korman, a towering comic actor sorely missed since the demise of "The Carol Burnett Show," makes Leo not only wacky but genuine. Perrine has a nice, pixilated sparkle. The household is rounded out by Sue Ball as an amusingly sarcastic daughter, Julie Payne as a lazy maid, and Michael J. Pollard, straight from the "whatever-happened-to?" file, as one of the world's least handy handymen.

Beverly Hills is popular again as a subject for movies and TV shows in part because the economy is thriving and people who watch television don't seem to resent stories about the rich. Besides, Leo & Liz are new to wealth (he is a bra manufacturer who made it big when Madonna brought bras back, he says) and so an audience can identify with their quest to belong, to be part of a privileged society. If they haven't paid their dues, they have at least coughed up the entrance fee.

What "Leo & Liz" has going for it is an infectious strain of real merriment. This starts from the opening credits, to the tune of "Mister Sandman," and is supported by the buoyant musical score of David Frank. You're primed for a happy time.

Six episodes of "Leo & Liz" have been filmed. If the show is picked up by CBS, Korman wants it to be done on tape in front of an audience, rather than on film with a canned laugh track, like the first half dozen. He thinks this will lend itself to improvised comedy business and to a looser, jollier atmosphere. He's probably right, but even so, "Leo & Liz" gets off to an awfully good start. It's a bucket of blueberries, and only a few of them ringers.