Less than two months after frantically excising any allusions to terrorism, network executives are scrambling to add terror-related storylines to TV shows, sources reported Monday. 'We're working around the clock to squeeze in a special episode where a Libyan with ties to Al Qaeda threatens to blow up the D.A.'s office,' said Law & Order producer Dick Wolf, who on Sept. 15 scrapped an episode of the NBC drama in which a character utters the word 'bomb.' 'We've got to stay on top of this thing.' Next week, Spin City, which last month pulled an episode featuring a shot of the World Trade Center, will air a 'very special' one-hour episode in which Mayor Winston is infected with anthrax. 