Look out, presidential and first-lady hopefuls: Trash-talking fashion-police chief Joan Rivers will be covering the political conventions for cable network E!

"Everybody, including Senator McCain's wife, has a gay friend telling her what to wear. And McCain knows who he is! He can tell," Rivers told the TV reporters gathered here, referring to the Republican candidate's recent comment that he can recognize homosexuals "by behavior and by attitudes."

Joan and daughter Melissa, whose coverage of celebrity arrivals at the Oscars, Golden Globes and Emmy trophy shows delivers that network's biggest audiences, will scout for fashion faux pas at the Republican National Convention in Philly in July and, a month later, at the Democratic parley in Los Angeles.

"We're here to help--not to hurt," Rivers hastened to add.

So says the woman who thinks nothing of telling Lara Flynn Boyle, on camera at the Golden Globe Awards, that her pricey white satin number looks like "a slut's wedding dress." Or touching the ample breasts of former "Baywatch" babe Traci Bingham at the Emmys to see if they're real. But only after asking--and, incredibly, receiving--permission of their proud owner.

According to John Rieber, E! senior VP of original programming, ever since John F. Kennedy turned up at the first televised presidential debate looking oh-so-handsome, and his GOP rival Richard Nixon didn't, "the way they look is as important as anything they say."

As is, Rivers added, how their spouses look. "Bess would have highlights and lowlights if Truman was running in 2000," she said. "And Mamie--those bangs would go!"

Their convention coverage, Melissa Rivers says, will include a look at presidential and first-lady styles--or the lack thereof.

She and her mom clearly are much more jazzed about the Democratic confab, which promises to be movie-star-studded.

The elder Rivers denies that her pre-Oscar celebrity cat-chats are crass. "The reason they're so popular is because we tell the truth," she said.

"I have yet to see one movie where they're not [fornicating] their brains out. . . . Our saying 'I don't like your shoes' is not bad taste."

Ellen DeGeneres says she'll be playing herself in her new pilot for CBS. Therefore the character will be lesbian.

She describes the program as a sort of "Carol Burnett Show" meets "Larry Sanders Show."

"I just want to do old-fashioned, funny sketch comedy and the behind-the-scenes of it, and me being the host of the show," she explained. So "you won't have to see me holding hands with anybody or anything," she assured the largely male contingent of reporters and critics.

The stand-up comic turned sitcom actress still thinks that her ABC series, "Ellen," was canceled because her character came out the same time DeGeneres did personally, not because the show got lousy ratings (with the notable exception of the coming-out episode).

But DeGeneres acknowledged that she handled the axing badly, including trashing ABC and saying that she and Anne Heche were going to leave Hollywood.

"There are things that I acted out publicly that should've just been my grieving period alone in my corner of my basement, rocking, naked," she said.

DeGeneres and Heche, as well as Sharon Stone and "Dawson's Creek" star Michelle Williams, came to the winter press tour to talk about the making of HBO's upcoming "If These Walls Could Talk 2." The program takes a pro-lesbian position, looking at the issue from the '50s through the present. The first part in the "If These Walls" trilogy, which aired on the pay cable net in 1996, touted abortion rights and starred Demi Moore, Sissy Spacek, Heche and Cher, among others. It was the highest-rated movie on HBO ever.

And yes, the sequel features a couple of girl-on-girl sex scenes. But self-described "expert on salacious material" Stone, who plays DeGeneres' partner and the mother of their child, says that viewers who are drawn to the telecast just for the sex scenes "are going to have to watch more than that to get to that," so the project "has value."

Winners List Annex: Numbers are in for the Sunday season debut of HBO's mob drama "The Sopranos." About 7.6 million viewers tuned in--the show's biggest audience yet and 121 percent above last season's premiere. (That 10 million figure you may have been hearing in connection with last season's finale was a cumulative number from multiple telecasts; the first run of the finale scored 5.2 million viewers.)

America's Voice, the Capitol Hill-based public affairs cable network, filed for Chapter 11 bankruptcy protection last week, dismissing about a dozen producers and technicians and putting most of its original programming on hiatus.

Although the network, available part time on cable systems in the District and Fairfax County, will remain on the air, marketing director Jim Halling said it will be showing reruns of a majority of its original programming, including talk shows hosted by Mary Matalin, Susan Molinari, Robert Novak and Armstrong Williams. The network does promise live coverage next week from the Iowa caucuses and New Hampshire primaries.

Richard Gross of Rosenman & Colin, the network's bankruptcy counsel, told The Post's John Maynard that "several sources" are interested in the possibility of merging with or purchasing America's Voice.

The network was founded by conservative Paul Weyrich in 1993 as National Empowerment Television. It changed its name and focus in 1998 when it came under the leadership of CEO Robert Sutton. Today America's Voice has 11.1 million cable household subscribers nationwide and reaches about 330,000 subscribers in the Washington area.

David Letterman strolled out of the hospital Wednesday after successful heart surgery, but questions remain about when he'll return to "Late Show" and whether someone will guest-host in the meantime.

"We really have to wait and see when Dave can come back before making any future plans," CBS spokesman Chris Ender told Maynard. "We're going day by day."

All next week CBS plans to air reruns featuring on-the-road "Late Show" broadcasts from the past five years. Ender says no programming plans have been made beyond that.