Former "SCTV" and "Saturday Night Live" comedian Short will be playing an eccentric attorney in an arc that will last "at least three episodes," according to Showtime.
"Prime Suspect" star Quinn, meanwhile, will appear in at least four episodes as "a charismatic investment firm CEO."
Sloane, of "She's Out of My League" and the WB comedy "Grosse Pointe" has signed on as eccentric conceptual artist Maxeen.
For the series' seventh season, which is currently under production and will premiere June 27, the show will take a three-year leap ahead from where the previous season left off, picking up with widowed mother-turned-drug dealer Nancy Botwin (Mary-Louise Parker) being released from prison and completing her parole in a strictly-run halfway house.
The series has also been relocated to New York for the upcoming season, after stints in the fictional California towns of Agrestic and Ren Mar.