NEW YORK — In what amounts to a fantasy pairing for New Line Cinema, the studio is in talks with Ron Howard to direct Jim Carrey in the remake of “The Secret Life of Walter Mitty,” sources said.If their deals can be made and Howard and Carrey agree on the script, the pic could be in production by spring. Such a pairing would be a first for Howard and Carrey. Imagine Films, in which Howard partners with Brian Grazer, produced Carrey’s latest hit comedy, “Liar Liar,” directed by Tom Shadyac. It’s likely that Imagine’s Grazer would come on board as producer, as he and Howard work so well together. Samuel Goldwyn Jr., whose father’s company produced and distributed the original Danny Kaye pic in 1947, currently is the sole producer. Hiring Howard would be a major coup for New Line, where the film has been shepherded by executive vice president Richard Saperstein and production prexy Michael De Luca. The studio’s hope has been to get the film into production in time for Christmas 1998. Grazer and Howard have strong relationships with the “Mitty” screenwriting team of Lowell Ganz and Babaloo Mandel, who have just turned in the first draft. The writers, who penned the Howard-directed “Parenthood,” have headquarters at Imagine. New Line agreed to develop the film for Carrey after agreeing to pay him $20 million against 20% (Daily Variety, Aug. 26). Carrey would play Mitty, a timid man who, in daydreams, becomes a brave, swashbuckling hero. Eventually he gets to realize that role. Howard is repped by CAA.