They're still working on the score (though they had a developmental workshop some time ago,) but word last month was that Megan Mullally has been approached and showed interest once they have a finished project to bring to the table.
She alluded to some impending offers in a recent interview with Broadway.com, and it is believed THE FIRST WIVES CLUB is one of the things she is hinting at:
"As for the theater, I have offers for a couple of big Broadway things (top secret!), depending on what happens with the pilot. They're both a year or two down the road."
Her pilot was not picked up, so she looks likely to be available.
Tonya Pinkins: Then we had a "Lot's Wife" last June that was my personal favorite. I'm still trying to get them to let me sing it at some performance where we get to sing an excerpt that's gone.
Tony Kushner: You can sing it at my funeral.