McCann has had a long and creative career. He started writing in high school for the student newspaper and acted in stage productions there. He has performed in and directed plays, a portion of them at El Camino College, others at various venues in L.A. William Peter Blatty, author of The Exorcist, once called McCann his "theatrical Godson," after McCann wrote and directed a stage adaptation of Blatty's The Ninth Configuration. McCann was also involved with stand-up comedy group The Big Mac Theatre, (who opened for such groups as Oingo Boingo, Canned Heat and Cecilio & Kapono), worked on independent films, designed sets, and did his own art on the side. In the early 1990s, McCann was an editorial director, artist, and writer for Cult Press, an independent comic book company.

McCann usually had to work the daily grind to support himself and his family, his creative aspirations becoming more of a hobby. But, while working at Diamond Comics in the mid-1990s, he was offered a writing job by former Cult Press owner Robert Graff, co-founder of Goldstar Events, who was then working as an editor for Warner Bros. Worldwide Publishing, which created, in addition to many other publications, children's comics for DC Comics. In February, 1996, Animaniacs #10 was published, with McCann's story "The Ice Cream Man Cometh." This story launched McCann's career as a professional writer. Eventually, McCann was able to quit Diamond Comics, to make a living by his writings alone.

McCann participates in many activities, encouraging youths to appreciate their own writing talents. He has taken part in the Alta Vista School's Student Writer's Conference since 2005, teaching workshops where he gives writing tips. He is known to reply to almost all of his fan mail.

He currently resides in El Segundo, California with his four cats, two children, and one wife.