The first rule in the TV game, as Charlie Grace might observe in one of his voice-over monologues, the first rule is that you don't want to have a time slot that puts you on the air against an established hit. The second rule in the TV game is that you don't want to be on opposite two established hits. "We have a rough time slot," said Mark Harmon of ABC's "Charlie Grace," in which he has the title role of the former-policeman-turned-private eye. The series airs at 8 Thursdays opposite new-hit "Friends" and old-hit "Murder, She Wrote." "It will take some patience from viewers and the network alike to find an audience that will tune in weekly to see the characters develop," he said. "It's a character-driven piece." One of the characters helping with the driving is that of Grace's daughter Jenny, played by Leelee Sobieski. "When you sit in an office and watch 35 11-year-olds come through the door, it's so good to see one who can take the material and elevate it and see things you didn't know were there," said Harmon. Sobieski, now 12, has gone to school in France, Miami and New York, and has had parts in the TV movies "Reunion" and "Saratoga Summer," and on PBS's "Sesame Street." One of her ambitions is to learn Polish and one day reclaim the Sobieski family palace in Poland. Harmon co-created the show with Bob Singer, who created Harmon's last series, "Reasonable Doubts." Harmon, who has played roles from the likable to the loathsome (Ted Bundy), believes viewers will find Grace a multifaceted man, funny at times, and a father who doesn't always have the answers. That is, if they can stop laughing at "Friends" and break the "Murder" habit. CAPTION: Leelee Sobieski and Mark Harmon of "Charlie Grace."