Delacorte senior v-p Leslie Schnur has snagged Colin Quinn, currently making waves as the "Weekend Update" anchor on TV's Saturday Night Live, for an untitled book to be published next fall. Quinn, who has just completed a sold-out run of a one-man Broadway show, An Irish Wake, says his aim is to "debunk, renounce, arrest, indict, convict, sentence and execute all that is out current societal nightmare." Dan Strone at William Morris was his agent for the deal.