Listening to its writers talk about "Paper Doll" is not unlike trying to follow the back-and-forth action of a rapid game of Ping-Pong.

For four years, playwrights Mark Hampton and Barbara J. Zitwer have been working on "Paper Doll," which is in previews for Friday's Pittsburgh Public Theater opening.

While never actually interrupting each other, these highly verbal, smart and very funny playwrights blend the dialogue of two into a seamless monologue as each contributes to a topic.

Zitwer is explaining that the structure of "Paper Doll" reminds her of a painting that, from a distance, looked like a traditional black-and-white portrait of a woman. It was only when she examined it closely that she realized the figure was composed of carefully arranged children's handprints.

"This play for me is the reverse," she says. "It starts with all these handprints of information and modules that by the end become one piece. By the end we see ..."

"... a portrait ...," says Hampton.

"... of the woman," finishes Zitwer.

Neither acknowledges or even seems aware that they are thinking in tandem.

"We've been working on (`Paper Doll') for four years. Mark, he's my husband in writing," Zitwer says.

"We both have other life partners, so we're like bigamists," Hampton jokes.

Having her life story made into a play by literary bigamists trysting with words in theaters, restaurants and hotel rooms would likely appeal to the play's central character. "Paper Doll" follows the later life of businesswoman, cultural icon and author Jacqueline Susann, best and most fondly celebrated as the queen of trash novels with lurid titles such as "The Valley of the Dolls," "Once Is Not Enough" and "The Love Machine."

Zitwer became interested in Susann while Zitwer's father was dying of cancer.

At the time, few people knew Susann had cancer. Even while Susann was undergoing radiation, she put on her gown and her eyelashes and went out to sell her books, Zitwer says.

"The way she faced cancer and medical challenges in her life gave me a lot of courage for facing my own situation," Zitwer says. "She made me laugh because she was so outrageous.

"I identify with her because she's a woman, a maverick. People gave her a difficult time, and she succeeded against every odd."

Telling the story of Susann's life allows Zitwer and Hampton to explore serious ideas of life, marriage and love, Zitwer says.

"But I would classify it as entertainment," Hampton says. "I was hoping when you heard the topic, you didn't think it was funny, because it would be a nice surprise."

Both Susann and her husband-manager, Irving Mansfield, lived their lives as though they were in show business, Zitwer says. "She would say, `My books are a show, and I come out and act.' ''

When Susann first started publicizing her books, she revolutionized and scandalized the stodgy world of publishing. Steamy sexual indiscretions, vast quantities of liquor and pills and glamorous people living a fast-paced, dazzling life cascaded from her paperbacks.

But she became a best-selling author not just by writing sassy novels. She was not shy about going on television talk shows, getting her name inserted in juicy gossip columns and being linked with famous and infamous people.

She also instituted the now common concept of the book tour. She traveled across the country to meet fans in towns that weren't New York, Chicago or San Francisco. She sold her novels through personal contact, copy by copy and reader by reader.

"It was the Jackie and Irving show," Hampton says, pointing out that the play's director, Leonard Foglia, uses the idea as his concept for the play.

What kept Susann going was the unflagging support of her husband and manager. Zitwer and Hampton are getting that same sort of backup from Foglia and the play's two stars, Marlo Thomas, who plays Susann, and F. Murray Abraham, who plays Mansfield.

"We had the sense between Barbara and me that the structure was very fluid," Hampton says. "We would like to see almost a film onstage. That's what Lennie (Foglia) is achieving with this."

Says Zitwer, "It's his imagination that has allowed it to go from page to stage."

Hampton says, "He's elevating us, saying `It's too sit-commy. You can go deeper.' The play has grown since we've been here (in Pittsburgh)."

During early rehearsals, the pair rewrote and reworked scenes daily. In fact, Hampton says, the 89-page script that they began rehearsals with shows replacement marks on 50 of its pages.

"We've hit our stride here," Zitwer says. "Now it's really happening, coming together."

Working with the actors and their questions has helped to clarify many scenes. "Marlo thinks like a writer because she's a writer and executive-produced her own TV series when women didn't do that," Hampton says. "Murray, just in reading monologues, made me cry. His acting and depth, even the funny monologue, I was so moved. You knew (his character) was a man who was trying to figure things out, and he loves his wife. He's absolutely brilliant."

Not every idea or inspiration works, of course. Zitwer and Hampton spent a considerable chunk of time developing a dream sequence musical number for Abraham and Thomas based on Sonny and Cher singing "I Got You, Babe." Full of enthusiasm, they tried it out one night on Foglia, complete with a blaring ghetto-blaster tape player.

The director rejected it.

But the next morning, Zitwer discovered that something Foglia had said had led her to create a whole new character. "Even the worst ideas, you wrack your brain and something can come from it," she says.

A week before first previews, the script was ``frozen'' so the actors could polish their performances. Zitwer and Hampton could hardly wait for the first audiences to get a look at it.

"They'll tell us what it's really about," Zitwer says.

As she waits for that feedback, she already knows where "Paper Doll" is headed: "No question, we're going to Broadway," she says.

Hampton is more cautious.

"I think there's a big new step before Broadway," he says.

"I don't know if we need another city or two in between. But we're on our way to Broadway," Zitwer says. "Open up, Shubert Alley. Here we come."