Dennis Leary and the rest of the crew from FX’s “Rescue Me” have returned to the firehouse early, producing a 15-minute special that will be used to promote the new season of the FX hit on a variety of nontraditional digital media platforms.

In a groundbreaking deal, FX and “Rescue Me” producer Sony have agreed to create the original, scripted content, which was being shot late last week, sources familiar with the project said. FX and Sony officials declined to comment on the project.

Increasingly, networks are asking the producers of the shows on their schedules to produce additional original content that can be used on digital and on-demand platforms as advertising vehicles and for promotional purposes. These deals are most easily made when both the network and production company have the same owner, as with NBC Universal’s “The Office.”

Sony and FX are holding discussions with distributors outside of the News Corp. or Sony family to put the original content on platforms such as broadband, video-on-demand and mobile phones beginning in mid-May, sources said. Season three of the series is due to begin on FX in June.

The companies are seeking mass distribution to generate millions of dollars in promotion value from the production and also to generate incremental revenues by selling an ad that would accompany the special installment of the show.

It is unlikely that the story, which involves the firefighters searching for a possibly wild animal that has invaded their firehouse, will appear on FX. It might be included as bonus material on the season three DVD for the program.

What FX and Sony are doing is not completely without precedent. Last year Fox and 20th Century Fox Television created a special episode of “24” before the fifth season premiere that bridged season four and season five. That special episode appeared only on the DVD and was never distributed in other media.

The special installment of “Rescue Me” is likely to be seen by more people, if the talks FX and Sony executives are having with broadband portals, cable operators and other distributors are successful.

Other networks have promoted their shows by putting their pilots online with portals including AOL TV, Google, Yahoo and MSN.

FX has been creating original material to promote its other shows and is interested in turning those promotional activities into opportunities for advertisers to extend their relationships with the network’s original programming.

Later this year, FX plans to make its original shows available on-demand via DirecTV for $3.99 per episode. The network plans to sell ads on those programs to advertisers looking for exclusive, uncluttered access to fervent fans of the shows.

FX also created a music video of the “Black. White.” theme song “Race Card” by Ice Cube to promote the documentary series. The materials appeared on MySpace.com, Yahoo, AOL, TVGuide.com and BlackAmericaWeb.com and on cellphones via Sprint, Nextel and Boost Mobile and its partner GoTV. “Black. White.” became the top-rated basic cable series premiere in the 18 to 49 demographic this season, according to Nielsen Media Research.

At the end of last season, FX created original material for its series “Nip/Tuck” that ran on a MySpace.com page based on the show’s character The Carver. The “Nip/Tuck” finale was the highest-rated show in 18 to 49 in FX’s history.