It's a very different thing to be onstage, facing a live audience--not what most film actors are accustomed to. Yet Andrew McCarthy has come a long way since "Pretty in Pink" and "St. Elmo's Fire." As the narrator-son in Warren Leight's memory play "Side Man," McCarthy sees his "job at the beginning is to sort of welcome them and to let them know that they're in good hands."

After 15 years as an actor in mainstream and independent films ("Mrs. Parker and the Vicious Circle") and onstage, this year McCarthy has worked steadily and almost exclusively in Broadway and prestigious regional theater. Before joining the Broadway run of "Side Man" last summer, McCarthy performed in Eugene O'Neill's "Long Day's Journey Into Night" and Horton Foote's "The Death of Papa" at Hartford Stage.

The shifting of gears from film to stage isn't easy. "If you haven't been doing theater for a while, and you get up onstage," he said, "your chops are hanging"--a jazz musician's term for being out of practice. "It's an entirely different use of concentration and use of energy."

Nowadays, that old Hollywood Brat Pack image comes up only when journalists mention it. "People sort of pigeonhole you and put you where you made an impression on them," McCarthy said. He's just ignored it and kept acting. "This is what I do. . . . I've never been much of a critics' darling, anyway," he said.

Actually, that's changed, too.

Starring with McCarthy in the Kennedy Center production through Nov. 28, Michael O'Keefe plays jazz sideman Gene, so dreamily absorbed by his trumpet that he does emotional harm to his wife and son. (Both actors note that Gene is based on playwright Leight's father.)

"It's the learning experience of a lifetime," O'Keefe said. "There's no way to convey to you the difference between me and Gene, but it's huge. . . . When I try to draw Gene out of who I am, it's one of the bigger challenges I've ever experienced as an actor."

Gene's a long way from O'Keefe's role on "Roseanne," or in the movie "The Great Santini," or in the recent off-Broadway revival of "That Championship Season." However, the actor did find a connection between Gene's detached self-absorption and the natural narcissism of actors. "We're very much kind of caught in the cult of our own personality," he said.

O'Keefe, who's married to singer-guitarist Bonnie Raitt, said he doubts she'll catch the show in its short Washington run. They must be a busy couple. Asked where he makes his home, O'Keefe said with a dry laugh, "I have no idea."

To Be, Be, Be, Be . . .

The Melancholy Dane is a man of many parts in director Joe Banno's psychological modern-dress "Hamlet" at the Folger Theatre. He's played by four actors, three of them women in men's clothing, as a way of emphasizing the warring elements of Hamlet's personality.

Holly Twyford plays the "central" Hamlet. "I've tried to consciously modulate my voice a little bit, because I know that it has the ability to get up there. But now, it's just kind of getting hoarse," she said on the phone after opening night last week.

The other Hamlets--Cam Magee, Kate Norris and Steven Carpenter--come and go through mirrored doors. They may cut in and finish a speech, alternate lines with Twyford, or speak in unison. Sometimes they hover, like the proverbial good and evil angels, vying for Hamlet's soul.

Hamlet's alter egos represent a line of Ophelia. "O! what a noble mind is here o'erthrown: The courtier's, soldier's, scholar's, eye, tongue, sword . . ."

Magee, who as dramaturge edited the text to fit Banno's vision, plays Hamlet-eye. She views this as his spiritual self--"the philosopher, the mind's eye; the one that's fixated on death; the melancholy one.

"I think part of Hamlet's journey is making his peace with death," Magee said. "I don't think until he gets to the gravedigger's scene and confronts the skull of Yorick that he really understands what death is."

Carpenter plays Hamlet-tongue--the talker, who sees both sides of every question. "He's the one that uses logic. That's why in the 'To be or not to be,' I'm the one that isn't ready to shoot myself," he said. "What's been interesting and difficult on some levels is trying to create a character out of a [single] personality trait."

Norris plays Hamlet-sword, often with pistol drawn. She's "the overemotional Hamlet . . . the one who just wants to do something." She thinks the four-Hamlet concept works. "What I'm hearing [from audience members] are words like 'clear'; they catch things they haven't seen before, because it is separated," she said.

Twyford agreed. "I think there are certain places where it just illuminates the text so much, and really blows [it] out of the water."

It's still a little weird, though. "There are times when I'm watching another one of me; or depending on whom you talked to, it's me being watched by me," Twyford said.

"We have so much fun on this thing," Norris said; "there are so many times when we're trying to figure out what we're going to do. . . . What if Holly stubbed her toe? Would all of us grab our toe?"

Follow Spots

* Kate Skinner, who plays Julie Cavendish in "The Royal Family" at Arena Stage, fainted at the start of the second act Sunday evening. The show was stopped and the audience promised tickets for another night. Skinner is expected to go on when the stage lights up again tonight.

* Studio Theatre has filled the gap in its spring schedule. They'll do "Bash" (March 1-April 9) by controversial filmmaker Neil Labute ("In the Company of Men" and "Your Friends and Neighbors"). "Bash" is a set of three one-acts, again about people's misbehavior toward one another. Studio will also perform "Betty's Summer Vacation" (May 17-June 25) by Christopher Durang, who is the theatrical thorn in the side of the Catholic Church for plays like "The Marriage of Bette and Boo" and "Sister Mary Ignatius Explains It All for You."

* Ford's Theatre has announced the rest of its season following "A Christmas Carol." Marcel Marceau, the French mime, will perform Jan. 25-Feb. 13, followed by James Whitmore in his one-person "Will Rogers' U.S.A.," Feb. 15-27. "Reunion: A Musical Epic in Miniature," with music from the Civil War era and the words of Abraham Lincoln, Frederick Douglass and others, will play March 7 through June. It's performed as a play-within-a-play involving an 1890s vaudeville troupe. Call 202-347-4833.

CAPTION: Former Brat Packer Andrew McCarthy, left, stars with Michael O'Keefe in "Side Man" at the Kennedy Center.

CAPTION: From left, Cam Magee, Steven Carpenter, Holly Twyford and Kate Norris portray conflicting elements of Hamlet's personality at the Folger Theatre.