WJLA has come up with a bright idea to boost viewership on its evening newscasts--and it doesn't involve dumping anchors.

Starting tonight, the ABC station will offer its Monday-through-Friday newscasts at 5, 6 and 11 p.m. in Spanish, native tongue of the fastest-growing segment of the U.S. population.

If all goes well, the Albritton-owned affiliate may expand the service to its morning newscasts.

To tune in, Channel 7 viewers need only select second audio program (SAP) on their TV sets. It's a service that the ABC network already offers on some sports programming, including "Monday Night Football," and recently tried out on the broadcast of the feature film "Selena."

The idea, says news director Jim LeMay, came out of general discussions that station executives had with members of the Washington area Hispanic community.

Spanish-speaking households represent about 6 percent of the area market--or about 100,000 homes. Snagging a significant portion of that audience could mean the difference between third place and first for Channel 7's evening newscasts.

For example, the 5 p.m. news race is very tight in this market, with No. 3-ranked WJLA this season averaging 106,500 homes--only 5,000 behind front-runner WRC-Channel 4.

At 6 p.m., WJLA trails first-place WRC by about 52,000 homes, and at 11 by about 78,000 homes.

The Spanish-language option may not just attract viewers who speak only Spanish; it could also drain some bilingual viewers from competing stations. From September '98 through February '99, leader WRC's 5 p.m. newscast averaged 11,000 Hispanic viewers and its 6 p.m. newscast 17,000. WUSA-Channel 9's late-evening newscast was No. 1 among Hispanics, averaging about 13,000 viewers.

"We hope that there are people out there for whom this provides a service they're looking for," says WJLA General Manager Chris Pike.

Advertising for the new service will begin running in Spanish-language media outlets next week.

Viewers watching WJLA's Sunday broadcast of the animated Disney movie "Lion King 2" got a little something extra. During a period of about 15 minutes during the two-hour movie, an 800 number periodically scrolled across the picture. It was the number for a phone sex line.

General Manager Pike says the station received 50 to 100 calls of complaint on Sunday.

WJLA had taped the broadcast earlier in the day off a satellite feed from ABC. But in addition to picking up "Lion King 2," the station's antennas also picked up traces of a concurrent feed--which was adult fare. While the programming itself was scrambled and could not be seen on the tape, the phone number periodically could be seen faintly.

ABC says the problem lies with the station's antennas, while WJLA says it's never had a problem before and faults the satellite provider.

At any rate, Pike says he takes the mishap very seriously and has taken steps to ensure that it doesn't happen again.

The longest game in major-league postseason history wreaked havoc on NBC's scheduled Sunday night lineup.

The New York Mets' dramatic 15-inning, 4-3 victory over the Atlanta Braves in Game 5 of the National League Championship Series lasted an astounding 5 hours 46 minutes, ending with a bizarre grand-slam single just before 10 p.m.

It also proved to be a ratings boon for NBC. The broadcast averaged about 16 million viewers, according to early estimates. That's NBC's highest rating for an afternoon league-championship series game since 1987, an NBC representative told The Post's John Maynard. In its final half-hour, 52 percent of New Yorkers and 65 percent of Atlantans who were watching TV were tuned in to the broadcast.

The historic game, in which management from both teams used every player on their rosters, had NBC programming management fiddling with its own lineup late into the evening and eventually dumping the highly touted movie "Mr. Rock 'n' Roll: The Alan Freed Story."

"We were calling audibles all night," said network scheduling chief Preston Beckman. "Every half inning, we were playing it out. . . . We kept changing the scenario until what happened happened."

Here's what did happen: With a 4:09 p.m. start time, NBC programmers figured reasonably that the game would be over in time for "Third Watch" to air at 8 p.m. But when it became clear that the game was going well into extra innings and beyond 8 p.m., the NBC paramedic drama was pulled, becoming the first casualty of the night.

The next plan was to air a shortened "Dateline" until 9 p.m., when "Mr. Rock 'n' Roll" was scheduled to begin. But that plan was scratched when the game continued past 9 p.m. under the lights at rain-soaked Shea Stadium.

NBC hoped it could still air the movie even if that meant starting it later than 9 p.m. But as The Game That Didn't Want to End approached the six-hour mark, NBC decided to silence "Rock 'n' Roll." "As it turns out, we could have gone with the movie at 10, but it would've been a disservice to the movie," Beckman said.

Actually, the preemption of "Rock 'n' Roll" may have been a boon to viewers, based on the reviews that nearly universally panned the movie, starring Judd Nelson as disc jockey Freed.

But both the preempted episode of "Third Watch" and "Rock 'n' Roll" will air Halloween night beginning at 8 p.m. Unless there is a Game 7 of the World Series.

CAPTION: "Mr. Rock 'n' Roll: The Alan Freed Story," starring Judd Nelson, was a casualty of Sunday night's marathon National League Championship Series game.