Melissa, have you checked out Tammy’s blog about her experiences with Pamela, her daughter? She has some wonderful ideas and descriptions scattered through her posts that might be helpful to you. Very CM friendly; very autism helpful!
On a related note, I must share a narrating victory I experienced today with Hannah, my 11yo with autism. She has other developmental delays too, so she’s operating on more of a 4 or 5 year old level, I would say. Anyway, you can read my description of her progress in narration on my other blog, Intentional Parents. I hope it at least encourages you to keep going. 