How To Write A Musical Film Script . 2) flesh out the story. If possible, get access to a piano or an instrument that is important in the musical's score. How to Write and Format a Musical Feature Screenplay ScreenCraft from screencraft.org It is the placement of the musical numbers that is key. Rouben mamoulian, the original stage director of oklahoma and carousel wisely said, it's the basic. If possible, get access to a piano or an instrument that is important in the musical's score.