Author David L. Bruce, who is now at the University of Buffalo, completed a study of four low achieving boy writers. His research was published in the July 2008 issue of Reading and Writing Quarterly.
The research method used in the article is described and the best parts are the transcripts of his discussions and anecdotes from the boys directly. The boys share with the author their methods of writing using film, audio and media.
Perhaps your school district has a subscription service in order for you to read this 20 page article. Unfortunately, due to copyright restrictions I am unable to link or post to the entire article.
Again, this is the best article I have read on motivating and engaging boy writers in quite a while.