Deadline reported O'Connell would play the Happy Mondays frontman and Isaacs would play his musician father Derek.
The 1980s alt-rock band is known for its hits "Hallelujah" and "Mad Cyril."
Variety said Holliday Grainger is in negotiations to play Ryder's girlfriend and Maxine Peake is up for the role of his mother in the film.
The project was announced at the Toronto International Film Festival on Friday.
Production is scheduled to begin in January.