FEMALE jazz musicians who appeared in the Julia Roberts hit Mona Lisa Smile are locked in a bitter legal battle with the toothy Tinseltown titan. Jeanne Daly, Jill McCarron, Ada Rovatti and Lauren Sevian, all New York area residents, say they were only paid half what they were promised for appearing as extras, and less than a male jazz band got. The irony is that Mona Lisa Smile is a prototypical 'chick flick' with a female empowerment theme. Set in 1953, it stars Roberts as a spunky art history professor who takes a job at all-female Wellesley College, and proceeds to persuade her husband-hunting students to strive for something more in life. Julia Stiles, Kirsten Dunst and Maggie Gyllenhaal co-star as students.