Gus Van Sant is directing the project to be produced by Steve Golin, according to The Hollywood Reporter.
Callahan became an alcoholic at the age of 12, a drug abuser in his mid-teens and a quadriplegic at 21 after being involved in a car accident after a day of drinking.
He managed to rebuild his life to become an envelope-pushing cartoonist, learning to use both hands to draw and also reconciling with members of his family. Callahan died in 2010.