For Charlton Heston, the opportunity to play Sir Thomas More in a filmed version of Robert Bolt's modern dramatic classic, A Man For All Seasons (6 and 9 p.m., TNT), was a long time in coming.

Twenty-two years, to be exact."I went after the part when they were casting the movie," Heston told television critics in Los Angeles recently. "But they said at the time that they wanted to offer it to the man who created the role on stage."

That would be Paul Scofield, the gifted actor who went on to win a Best Actor Oscar for his performance in the 1966 film about the moral conflict between King Henry VIII and Sir Thomas, Chancellor of England. Few who have seen that magnificent performance would argue with the decision to go with Scofield over the more widely known Heston - not even Heston.

"Paul Scofield's performance is definitive," says Heston, simply.

Still, when TNT offered Heston a chance to bring his stage version of the play to cable television with a cast that includes Vanessa Redgrave as Lady Alice More and Sir John Gielgud as Cardinal Wolsey, he jumped at the chance - Scofield's brilliance in the role notwithstanding.

"I'm not daunted by the images remaining from the film," said Heston, who also directed the TNT version. "As an actor you get used to the idea of following other actors. That's what happens to good parts. I've followed Sir John (Gielgud), Sir Ralph (Richardson) and Sir Laurence (Olivier) into Shakespearean roles before. It's never easy, but you soon learn that every actor makes every role his own just by virtue of his own uniqueness.

"I'm not Paul Scofield. I look different. My voice is different. I am different. So my Sir Thomas is different from his Sir Thomas, and this version of `A Man For All Seasons' is different from his."

But it's still Bolt's play, a wondrous work that focuses on More's conscientious stand for the rights of a private citizen which led to his loss of position, wealth, family, freedom and, eventually, life.

"When Robert Bolt sat down to write `A Man For All Seasons,' God must have whispered in his ear," Heston said. "I have been involved with this play since shortly after it was written, and I share the opinion that there has not been a better piece written since. Not only the structure of the piece, but the dimensions of the questions it explores.

"Individual versus social responsibility is the constant question posed in a democratic society," Heston continued. "Because the play makes an unavoidably contemporary statement, it is truly a play for all seasons."