Just as Buena Vista’s “Sister Act” approaches the $ 138 million mark in domestic box office receipts, Walt Disney Pictures has started production on the high-concept comedy “Hocus Pocus,” the studio announced yesterday.Starring Bette Midler, Sarah Jessica Parker and Kathy Najimy, “Hocus Pocus” is about three 17th-century witches transported to present-day Salem, Mass., on Halloween Night. After a 68-day shoot on the Disney lot, with locations in Salem, “Hocus Pocus” is earmarked for a G or PG rating. One source indicated the budget is in the “low 30s (millions),” which would be a departure from the studio’s cost-conscious strategy. A quintessential Disney project, the movie is designed to capitalize on the spirit of the Halloween holiday. The special-effects laden pic features a talking animatronic cat, one of the central marketing hooks for the movie. “Hocus Pocus” joins “Super Mario Brothers” the re-release of the animated “Snow White,”"Stakeout 2″ and the currently lensing “Beyond Innocence” on Disney’s schedule for summer– the season when roughly 40% of the year’s domestic box office is tallied. Other pix are expected to be added to Disney’s summer slate shortly. To be produced by Steven Haft and David Kirschner, “Hocus Pocus” will be directed by second-timer Kenny Ortega (“Newsies”). Kirschner wrote the “Hocus Pocus” story, which was purchased by Disney chairman Jeffrey Katzenberg and Walt Disney Pictures president David Hoberman in 1985. “Disney never let this project just sit,” Kirschner said. “They kept it in completely active development, constantly working on it” until it was ready to go. Co-producer is Bonnie Bruckheimer, while Ralph Winter carries the exec producer’s title. Midler previously starred in the company’s “Down and Out in Beverly Hills, “”Ruthless People,”"Outrageous Fortune,”"Big Business,”"Beaches” and the Goldwyn co-production “Stella” before traveling to 20th Century Fox’s “For the Boys.” Pic also features Thora Birch, Omri Katz and Vinessa Shaw. Kirschner, Hanna-Barbera Prods. chairman and chief executive, also is producing the Macaulay Culkin/Christopher Lloyd/Whoopi Goldberg starrer “Pagemaster” for 20th Century Fox.