Orson Welles' "Citizen Kane" is often acknowledged as the greatest film ever made. It was recently at the top of the American Film Institute's rankings.

So it takes no small degree of chutzpah to make a movie about the making of the greatest movie ever. And it's no small accomplishment that HBO's made-for-cable movie "RKO 281." which premieres Saturday at 10 p.m., is a fine telefilm indeed.It's the story of the battle between the "boy genius" -- Welles (Liev Schreiber) was 24 when he made "Citizen Kane") -- and mogul William Randolph Hearst, who, in his mid-70s, still wielded great power with his chain of newspapers. The story is of a hugely confident young Welles who ventured to take on and attempted to take down Hearst by making a thinly veiled and none-too-complimentary movie about his life.

While "RKO 281" (the title comes from the production number of the RKO film "Citizen Kane") is not an attempt to mimic the film it portrays, there are parallels. Told mostly from Welles' point of view, it employs newsreels and news headlines to tell his tale, just as the audience learned the history of the fictional John Foster Kane in "Citizen.)

And there's another parallel between "Citizen Kane" and "RKO 281" -- the former was a fictionalization of the life of William Randolph Hearst; the latter is somewhat a fictionalization of the former.

"It's important for me to remember that I'm a dramatist," said scriptwriter John Logan. "I'm not an historian. . . . It's my job, and the job of the creative team that I worked with, to find history, to examine it, to know dates and places, and then find the metaphors that were necessary to make a dramatic motion picture. I believe we did that."

But not everything in "RKO 281" actually happened. For example, the movie opens with Welles dining at Hearst Castle with the publisher, his girlfriend Marion Davies and a group of other people.

"Orson Welles was never at San Simeon," Logan acknowledged. "We make allowances. We telescope events. We move things around. It was necessary for us to do this to tell the larger truth we thought was implicit in the story."

(Given "Citizen Kane," it's hard to believe that Welles, at least, would object. But then Welles at least changed the names of his characters.)

"I don't know of any one person who spent more energy rewriting his own history than Orson Welles, and I think it's sort of appropriate in that vein," Schreiber said. "I read five different biographies on him when I was preparing to do the film, and I heard five different stories of what happened in the making of 'Citizen Kane.' "

The story of the making of the film is fascinating enough, but the story of Hearst's efforts to make sure it was never seen and Welles' counter-offensive is riveting.

"RKO 281" is well-written, and director Benjamin Ross ("The Young Poisoners Handbook") does a fine job with a great cast, which includes Melanie Griffith as Welles' mistress, Marion Davies; John Malkovich as alcoholic scriptwriter Herman Mankiewicz; Brenda Blethyn as gossip maven Louella Parsons; Roy Scheider as RKO studio chief George Schaefer; David Suchet as MGM chieftain Louis B. Mayer; and Fiona Shaw as gossip columnist Hedda Hopper. (Ridley Scott was one of "281's" executive producers.)

But it's the performances of Schreiber and Cromwell on which the movie pivots. And both do amazing work.

"I was very intimidated by the role and I wasn't quite sure how to handle it," Schreiber said. But he was sure that he didn't want to try to mimic Welles, just to try and capture his presence and spirit.

"Once you get into mimicry, the process then becomes about comparison rather than about storytelling," he said. "I kind of tried to avoid all of that.

"The first thing all of my friends asked me -- because all of my friends are insane film students -- 'Are you doing the voice?' And I say, 'Well, I hope not.' "

And Cromwell plays the villain of the piece as somewhat less than a black hat.

"His power interests me, but mostly I was interested in his vulnerability," said Cromwell, who added that he was interested in the script because it painted the story in shades of gray instead of in black and white.

"As a matter of fact, my interpretation was that Orson Welles decided not only to make a great film, but to flip the bird to Mr. Hearst and somebody that he cared deeply about," he said, referring to Davies. "And if (Hearst) had one good quality, it certainly was his faithfulness and his love and his concern for the woman who was in his life, and he refused to let any twerp get away with it."

And it's also interesting that neither Hearst nor Welles came out of their battle as a winner -- it damaged both of their lives and their careers.

"I think it's really interesting that we have an infantile gesture on the part of Mr. Welles, and we have a rather infantile response on the part of a man who has incredible power," Cromwell said. "And the two of them, in effect, bring themselves down. Hearst winds up always running second fiddle to Mr. Kane, and Orson Welles shot himself not only in the foot but in the heart."

Which is a tale that makes for a fine film.

"RKO 281" is not rated, but contains some R-rated language and sexual situations.