As out-of-town tryouts go, this one’s awfully good.

A brand new musical, “The Opposite of Sex,” based on the quirky 1998 screen comedy, opens the season at San Francisco’s Magic Theatre. For the show’s two Jewish creators, songwriter Doug Cohen and director/

co-author Robert Jess Roth, it’s the culmination of a dogged five-year effort to bring the story to the stage.

“Opposite” is not a “Jewish” musical by any means, though Roth (a former bar mitzvah boy from New Jersey) and Cohen (the Walnut Creek-born son of a rabbi) certainly have absorbed the rich Jewish legacy of the American musical theater. Both men now live in New York.

But why convert an admired, if somewhat obscure, independent film — that isn’t “Hairspray” — into a musical?

“The movie was playing down the street,” recalls Roth of the night he first saw the film. “I got swept up in the storytelling, and on the way home I thought, ‘This could be a musical.'”

Based on the screenplay by Don Roos, “The Opposite of Sex,” now in previews, opens officially on Saturday, Oct. 2. It tells the story of 16-year-old Dedee Truit (played by Christina Ricci in the film) who runs away to live with her gay stepbrother, Bill.

A natural born hell-raiser, Dedee soon wreaks havoc on Bill and his friend Lucia, seduces his boyfriend Matt and takes off with him, leaving a trail of emotional destruction from Louisiana to Los Angeles.

Not exactly Julie Andrews twirling in an Alpine meadow, but that’s the post-modern world as seen through the eyes of Cohen and Roth.

“We stayed true to the structure of Don’s story,” says Roth. Adds Cohen, “We borrowed liberally from the screenplay.”

Given the yeoman team effort required to mount a musical, both Roth and Cohen report the experience has been remarkably smooth, right from the start.

In early 1999, Roth first approached his friend Cohen with the idea. Roth was the highly successful director of the original Broadway production of Disney’s “Beauty and the Beast.” Cohen had written several musicals. The two had worked together on the off-Broadway show “No Way to Treat a Lady” back in the 1980s and had long wanted to work together again. “Opposite” attracted them both.

“I started writing little themes for various characters and situations,” recalls Cohen. “We didn’t want a conventional opening number. Ours would encompass a lot more. The lines Don Roos created seemed very lyrical. They were a great jumping-off point.”

“Doug would play the songs sitting at the piano,” remembers Roth. “They were so beautiful, funny and moving. Then we started weaving together the book. When we were done, we had our agents send it to Broadway producers; then we did readings that went well.”

Though Roth had had experience with the multimillion dollar musical, he was happy to scale things down for his new show. “All the bells and whistles of a big Broadway show are fun when they work,” he says. “But all that technology is time-consuming and can break. Here, we don’t have that.”

What they do have is a world-class creative team including musical director Brad Haak, Tony award-winning orchestrator Michael Starobin (“Assassins”) and set designer Derek McLane. The show stars Kerry Butler as Dedee and Tony award-winning actress Karen Ziemba as Lucia.

Early previews of “Opposite” at the Magic Theater have been nothing less than a blast for Roth and Cohen (though the latter took a High Holy Day break, attending services at San Francisco’s Congregation Sha’ar Zahav). Both enjoy the step-by-step process of perfecting their show.

“I like trying to find solutions,” says Cohen. “Rob and I are very proactive. Through the previews, we learn where we’ve overwritten. But we love implementing changes overnight. The cast is so quick and eager.”

After their Bay Area run, both have high hopes that the show will move to the opposite coast before too long. No one has a lock on Broadway, but Roth and Cohen like their chances.

“We’re putting in a lot of changes every day,” says director Roth. “Right up to opening night. That’s just the nature of musicals. But the show is running tighter now, and we feel ready to share it with the rest of the world.”

“The Opposite of Sex” plays 8:30 p.m. Tuesday-Saturday, 2:30 p.m. Sunday, through Oct. 24, at Magic’s Sam Shepard Theatre, Fort Mason Center, Building D, Laguna at Marina Boulevard, S.F. Tickets: $25-$50. Information: (415) 441-8822 or www.magictheatre.org.