A Celebration of Stephen Sondheim : Theater: A star-packed benefit at Carnegie Hall tonight is a sellout. The attraction: Two hours of his songs, including at least one new tune.

If Stephen Sondheim asked him to direct the telephone book, Scott Ellis said, he’d do it. And with Sondheim’s stature as a writer of musicals and Ellis’ growing reputation as a wizard at staging them, it would probably be a sellout.

As it is, Sondheim had an easier request: Would Ellis direct “Sondheim: A Celebration at Carnegie Hall”? You bet, came Ellis’ reply.

The result will be staged at Carnegie Hall tonight, one of those gala evenings dazzling with stars, crammed with chic and sold out days ago. The financial beneficiary will be Carnegie Hall, which expects to add several hundred thousand dollars--a more specific figure wasn’t available--to its treasury. The benefit to the audience filling Carnegie Hall’s 2,804 seats, and later to thousands more via television and recordings, will be two hours of Sondheim songs.

Some of the music will be seldom-heard pieces. Others will be standards given unusual twists. At least one song will be new, written by Sondheim for an upcoming Rob Reiner film.

“Steve’s had several of these shows,” Ellis said. “Our challenge was to make it as new and different as possible. The main thrust we’re trying to show is that Steve can cross into many areas--jazz, pop, classical, opera and, of course, Broadway.

“What we are doing is trying to find different ways of approaching ‘his music.’ ”

So “Broadway Baby,” that anthem from “Follies” so favored by singers of a certain age, will be sung by Daisy Eagan, the preteen who recently graduated from “The Secret Garden.” Glenn Close, better known for her high-powered acting, will show off her vocal skills with “Send in the Clowns.”

New vaudevillian Bill Irwin will introduce the evening and conduct the orchestra at the outset. In a departure from the usual salute to a composer, two ballet stars, Leslie Browne and Robert LaFosse, have joined the lineup.

The vocal range will stretch from the pop-rock group Betty and cabaret quartet the Tonics to the Boys Choir of Harlem, opera’s Harolyn Blackwell, and Eugene and Herbert Perry. Broadway regulars include Victor Garber, Michael Jeter, Madeline Kahn, Dorothy Loudon, Patti LuPone, James Naughton and Bernadette Peters.

Although Ellis is deeply involved in Sondheim’s work, he began his rise to hot-young-director status with the music of John Kander and Fred Ebb. He was in the cast of “The Rink,” their 1984 musical that starred Liza Minnelli and Chita Rivera. Three years later, he made his directing debut with a revival of Kander and Ebb’s “Flora, the Red Menace.”

The original production of that musical brought Minnelli to New York’s attention. The revival did the same for Ellis and his teammates, choreographer Susan Stroman, a Tony winner last month for “Crazy for You,” and writer David Thompson.

Director-producer Hal Prince, Sondheim’s longtime collaborator, was among those who saw “Flora, the Red Menace.” “He called me,” Ellis said, “and offered to help me out anyway he could.”

Prince was to have directed the New York City Opera’s 1990 production of Sondheim’s “A Little Night Music,” but had conflicting commitments. Sondheim, who had also seen “Flora, the Red Menace,” suggested Ellis for the job. The result was one of the most successful of the City Opera’s Broadway musical treatments. The production also reunited Ellis with Broadway conductor Paul Gemignani, whom he’d met on “The Rink.”

Tonight’s gala, which has been put together by the Ellis-Stroman-Thompson trio, plus Gemignani, will be taped and recorded live. PBS has scheduled it in its “Great Performances” series next March, when RCA will issue the recording.