When Gabriel Casseus was just reaching adulthood, he'd hang out in Harlem with Eriq La Salle and Ving Rhames and the trio would fantasize about success in show business. But while his cohorts became working actors and then hot properties, Casseus languished in Manhattan working in restaurants, playing the occasional guest roles in local filmed TV series, such as on "New York Undercover" (Fox, 1994) and "Law & Order" (NBC, 1994). The commanding actor also honed his craft on stage, appearing in regional theater productions of "The Amen Corner" and "Blues for Mr. Charlie", but some of his acting