Child killer Joel Steinberg has a cable-TV job waiting for him if he is released on parole next summer, his civil attorney said yesterday. Lawyer Darnay Hoffman, who is general counsel for the show, said he has arranged for Steinberg to work on "New York Confidential," a program planned for a leased-access Time Warner cable channel. Steinberg, 62, is serving 8 to 25 years for fatally striking his illegally adopted daughter, 6-year-old Lisa, in his Greenwich Village apartment in November 1987.