Jeff, I think a pretty good place to start would be Mary Stewart Van Leeuwen's "A Sword Between the Sexes? C.S. Lewis and the Gender Debates." Eldredge builds a lot of his arguments on stuff he got from Lewis, and Van Leeuwen does an excellent job of showing what influenced Lewis's thinking and how it developed over the years.
Eldredge (and that strain of masculine Christianity thinking) also take a lot from Robert Bly and the mythopoetic men's movement, so some reading in that area is helpful. There are some good essays in the collection "Women Respond to the Men's Movement," for example.
Looking a little further back to the development of some of these ideas in modern American Christianity, I found Margaret Lamberts Bendroth's "Fundamentalism and Gender: 1875 to the Present" and Betty A. Deberg's "Ungodly Women: Gender and the First Wave of American Fundamentalism" to be essential reading.
For an introduction to a different way to think about religion to give to someone raised on Eldredge, etc., my favorite book is Dorothee Soelle's Theology for Skeptics. (David and Sarah Dark introduced me to Soelle's work, incidentally). It's fairly short, and a good introduction to why using violent language and exclusively masculine language to talk about God is so often harmful.