DocumentationA description of the options accepted by
spatchis available here.
More examples are available here.
The Wiki contains more hints about using Coccinelle.
The LWN articles about Coccinelle may provide a useful introduction: Semantic patching with Coccinelle by Valerie Aurora, and Evolutionary development of a semantic patch using Coccinelle by Wolfram Sang. Eric Leblond has also written an article about his experiences.