"It’s going very well, it's in its early stages, and that's probably all I can say. We're really enjoying working on it," Menken told EW.
Menken's upcoming projects also include a stage musical adaptation of "Corrina Corrina" for Audra McDonald and the newly announced Roy Rogers musical Happy Trails, which is eyeing a 2016 Broadway arrival. He is a Tony Award winner for his score to Newsies.
Williams provided the voice for the Genie in the Disney animated feature "Aladdin," which Menken scored. The stage adaptation of the film arrived on Broadway last season.
Zippel is the Tony Award-winning lyricist of City of Angels. He previously collaborated with Menken on the Disney animated musical "Hercules" and "Mulan."
Fierstein, who appeared as Williams' gay brother in the 1993 film "Mrs. Doubtfire," has won Tony Awards for the books to Hairspray and La Cage aux Folles, as well as his play Torch Song Trilogy. He collaborated with Menken on the stage adaptation of Newsies.
"Mrs. Doubtfire" starred Williams as a man who impersonates a female housekeeper in order spend time with his children following a difficult divorce. Sally Field co-starred.