I'm still here though not using Moodle any more because I retired over 4 years ago. The exercises I put on Book are still on line here : Limericks: Stress & Schwa exercises. I don't remember exactly how I did it but it was very simple: basically I uploaded the exercises to Moodle and then linked to them from within Books so that they open in a popup window. I can give you teacher access to the course, if you like so that you can poke around to see how it was done. I did them originally for Moodle 1.9 but they seem to continue working fine on Moodle 2
Contact me privately - my email is in my profile - to get the ID.