Just a thought - there is a set of books called "You read to me and I'll read to you" (or something like that) with alternating paragraphs for parents and children. If the issue is that the role that Mommy is the reader and not the child, then these might be a fun way to get past it.

... I did a quick search:
http://www.amazon.com/You-Read-Me-Ill-Together/dp/0316363502