With his receding hairline topped with a mop of tight curly hair and a warm, inviting smile, Joey Slotnick seems perfectly at home in comedy, although he has also proven a capable serious performer. The Chicago-born and Las Vegas-raised joined The Rainbow Company, a local children's theater troupe as an adolescent. Hooked on acting, Slotnick studied at Southern Methodist University (where he won the annual Greer Garson Award in his senior year) before returning to his home town where he honed his craft with appearances at the Lookingglass Theater. After making an impression on director Penny