Hooray for Hollywood...where you're terrific if you're even good."

So go Johnny Mercer's lyrics to one of the most famous songs written about showbiz. The cast and producers of the Broadway musical Dream, opening April 3, know they have to be terrific to make it on Broadway, and they took the opportunity of an open rehearsal, Feb. 27, to show onlookers how terrific they can be.

In his opening remarks, director/choreographer Wayne Cilento (Tommy) praised the "so talented" cast and said he loved working on the piece because, "Dream lets me go wherever I want to go. We're telling a story entirely through Johnny Mercer's lyrics." Cilento also said that the production recently added a fifth section to its musical-historical overview, called the "Hollywood Section," and that this rehearsal would concentrate on that new material.

No sooner did he say "Hollywood" than four male cast-members took to the floor of the Raw Space Rehearsal Studio in New York and shared vocal duties on "Hooray For Hollywood." For the dance break, 6 male/female pairs, all in casual gym/dance clothes, moved around the dance space. The middle section featured a sexy, slow-motion solo for a dancer in red. Then Lesley Ann Warren joined the group for some sexy posing of her own.

"Accentuate The Positive" came next, as an extended dance number featuring the chorus reacting to various comic sound effects, such as yawns, car engines and dropping bombs. Margaret Whiting, in a striking orange sweater-suit, then came out to sing "In The Cool, Cool, Cool Of The Evening," accompanied by John Pizzarelli on back-up vocals and guitar, as well as piano and bass. Before beginning, Whiting reminded the assembled that in the show, she would be sitting on the piano, a la Michelle Pfeiffer.

Following Whiting's ballad, four sets of wooden tables and chairs were brought out to approximate the "Hollywood Canteen," with Darcie Roberts offering a zippy, "I'm Doing It For Defense."

Closing the rehearsal were Jonathan Dokuchitz and Jessica Molaskey sharing the vocal honors on "The Days Of Wine And Roses," with Cilento pointing out that the sequence would also feature a long staircase at center stage.

After the presentation, Whiting recalled meeting Johnny Mercer when she was just 7. Since her father was famed lyricist Richard Whiting, Mercer "was around the house a lot. He heard me sing, and first he said, `Grow up.' But he started working with me..."

Whiting also said that although we tend to give composers more prominence and attention than lyricists, which isn't always fair. To demonstrate, she hummed the first two phrases of "My Funny Valentine." "Lovely, yes? But when you add the words... Lyrics are the diamond in the setting. Johnny once told me the problem with a lot of new songwriters is they just don't do their homework. He once wrote a song and was told to come up with 15 choruses, [to be whittled down to four or five]. He wrote 25. Why? Because it had to be right."

Asked about the difference between singing in a cabaret environment and performing on Broadway, Whiting said, "If I sing in cabaret, I have to reach that one-to-one feeling. That stays the same, only I need the vitality and stamina to do eight shows a week."

Before the half-hour preview began, drummer Tony Tedesco told Playbill On-Line that he grew up with the swing and big-band music played in the show, and that it was a great feeling for him to actually play it. "The show has kind of a `greatest hits' feel to it."

Tedesco said his favorite song in the piece is "My Shining Hour": "It's generally given a swing-arrangement, but when Margaret sings it..."

Whiting said that a very specific memory haunts her when she sings that song. "I was singing for 100,000 troops in Palm Springs. These boys were being toughened up to go meet Rommel in the desert. What I knew, and they didn't know, was that they next day they were being shipped out. Oddly enough, the song I actually sang was "Dream," but in this show, it's `My Shining Hour.'"

Though she performed only one number at the rehearsal, Warren, dressed in a red, "98-ROCK" cut-off shirt and black leggings, stayed for questions and told Playbill On-Line she enjoyed being in a show that told an entire story through song and dance, while giving her the opportunity to play five very different characters. "The one least like me is the first," Warren said. "She's a corny Southern belle-type. But the character most like me...hmm... I think all the characters use different aspects of myself. I sing "Black Magic" and "Blues In The Night," which allow me to show my sexual and sensual side, which is very important to me; and on "Moon River" I get to be more vulnerable and little-girlish."

For more information on Dream, please see Playbill On-Line's story, "Dream Will Come True on B'way April 3." For tickets and information on the show, beginning previews March 11 at the Royale Theatre, call (212) 239-6200. You can also order tickets on Playbill On-Line.

--By David Lefkowitz