"Thirtysomething," ABC's yuppie-powered television series, is taking to the basketball court. The show is set in Philadelphia, and the Jan. 24 episode will feature members of the Philadelphia 76ers, including all-stars Charles Barkley and Maurice Cheeks and coach Jim Lyman, in a dream by Michael Steadman, the character played by Ken Olin. Most of the dream scene, in which Olin's character scores the wininng basket, was filmed last month in Los Angeles with the 76ers and now the crew is going to Philadelphia Wednesday to film crowd reaction in the Spectrum. Producer Scott Winant said he will be looking for "Go Steadman - Go Sixers" banners and the fan reaction a player would expect to receive after winning a big game at home.