The Wrap (via Film School Rejects) tells us the two comedians are joining Jason Biggs, Joel David Moore, Lauren Ambrose, Tom Arnold, Cedric the Entertainer, Christopher McDonald and Emily Bergl. Biggs will play Campbell, an ex-reporter who agrees to run his eccentric friend's (Moore) campaign for a seat on the Seattle City Council. Ambrose will be filling in as Biggs' girlfriend, Smulders a skeptic of Moore's absurd campaign, Arnold as a supportive bartender, and the Entertainer as the incumbent Moore is gunning for.
I haven't read Campbell's memoir, but the Amazon descriptions of the stories the author recounts have bumped it to the top of my to-read pile. The Wrap doesn't peg who Pierson (who doesn't spend enough time in front of the camera, if you ask me) is playing, but personally I'm hoping it's Campbell's roommate, described by Publisher's Weekly as an "off-center alcoholic with a new handgun he can't stop playing with."