"Lily: Sold Out," Lily Tomlin's first TV special in too many years, suggests how Woody Allen's "Stardust Memories" might have turned out if Allen hadn't been suffering guilt pangs for ever having made another human being laugh.

"Sold Out," at 10 tonight on Channel 9, manages some delicious, subtle, double-edged spoofery. Tomlin makes fun not only of garishly glitzoid Las Vegas entertainment but of her own record as a performer toting around a social conscience heavier than the Ile de France. Everything Tomlin has done for television since "Laugh-In" has been conceptually ambitious and risky, and tonight's hour on CBS is entirely within that tradition. You couldn't really call it a laugh riot, but even at shaky junctures it commands admiration.

"Sold Out" is a book show. It even has a plot. Lily Tomlin has just finished a high-minded Broadway revue called "The Seven Ages of Woman," and her agent tells her on the phone that he's landed her a booking at Caesar's Palace in Vegas. What makes him think the great lady of the stage would lower her brow to that level? "I don't think I could live with myself if I did something just for the money," she tells him.

But soon she is asking with incredulity, "How much? Is that per week?" Next stop Caesar's Palace!

She is greeted there by Alex Rocco, of all people (he played Mo Green, the Vegas major domo, in "The Godfather") and Melanie Mayron as a TV reporter who sticks a mike in her face in the same near-lethal way that ABC's Sam Donaldson thrust one at Jimmy Carter as he walked out on the Capitol steps for Ronald Reagan's inauguration.

Tomlin's misgivings about this career turn reach dizzying heights once she catches the act she's to follow: the imitable, mistakable, excruciatingly artificial Tommy Velour, Mr. Entertainment, who is actually Tomlin herself, eerily believable in Wayne Newton mustache and with Sammy Davis' mannerisms down to a T, or rather to a "ch-kunk, ch-kunk, ch-kunk-kunk-kunk."

When the curtain goes up on Tommy, he's already shouting "Pow! Pow! and "Hey, wow!"

His big finish is MacArthur Park," sung to a giant cake and with more accompanying fireworks than the 1812 Overture.

Johnny's act is a consummate, definitive parody and so close to the real thing that viewers tuning in late may merely think they've happened upon another lousy TV variety show. Lily's own act, which comes later -- and which merrily turns her feminist credo into vampy camp -- is something of an anticlimax. But unspeakably lavish, wildly watchable and very funny.

Guest stars who pop in for short stays include Jane Fonda as a bag-lady companion to Tomlin's own bag-toting Tess; Audrey Meadows as a wardrobe woman singing the praises of show-biz as if it were a cure for a long-incurable disease; Dolly Parton as a bountiful dowager; Harvey Lembeck, once a member of Bilko's platoon, as an hilariously obvious comic ("Mister Mickey Gold!"); and, briefly, Paul Anka, Liberace and Joan Rivers.

From the gallery of Tomlin characters come Ernestine the telephone operator, Mrs. Judith Beasley of Calumet City, Ill., as a tourist regularly phoning the kids at home ("Your daddy and I plan to start having fun soon"); and that fountain of homey platitudes, Bobbie Jeanine, who's landed a job playing the Hammond Organ at the Stopover Lounge in the Vegas Airport, where she not only sings and plays but provides "up-to-date flight information" as well.

The sort of audience-coddling "entertainment" dished out in Vegas and on many TV specials has of course been lampooned before, but here the satire seems laced with respect -- respect, maybe, for the pure mindless phoniness of it all, for the way any semblance of an honest human emotion is religiously avoided. To her credit, Tomlin makes her nobler, politically active side nearly as much of a joke as her whack at opportunistic groveling.

Producer Rocco Urbisci, director Bill Davis, and a number of writers (most of them women) fill the hour with funny and telling details and give it a ripe high gloss. Tomlin herself is still remarkably fresh, fascinating and resourceful, whether being shot from a cannon, doing a half-gainer into a tank of water, twirling herself into feverish modern dance movements to "Feelings," or dashing offstage during her finale to murmur into a hastily applied oxygen mask."Do you think they like me?"

There's something delicate, immaculate and sweet about "Sold Out," even when it's at its most outrageous. "Oh, gosh!" says Tomlin to a cheering crowd during her roof-rattling production number. "While we're all having fun tonight, we shouldn't forget about war." There's only one Lily, and it isn't enough.