The reunion was announced Thursday.
Also set to take part in Saturday's taping at the Hollywood Palladium will be Ellen Barkin, Wayne Brady and Gilbert Gottfried, the cable network said.
They will join the previously announced roasters, who include Carrie Fisher, Seth Green, Katey Sagal, Anthony Jeselnik, Jeffrey Ross and Amy Schumer. "Glee" star Jane Lynch will serve as roast master.
The comedy special is to air Aug. 12.