Did you consider my post from Jan 2011:
In case the link doesn't work:
I wondered why the "Add Map Box" item is not active in the "Modern Lines" theme (among others). After searching the forum for that topic I came across these two posts
which are unfortunately archived. As I needed a solution I started digging in the plist files as recommended in one of the posts above. The "Add Map Box" menu item is active in the "Photo Journal" and "Photo Essay" themes. After comparing the files Theme.plist in /Applications/Aperture.app/Contents/Resources/Book Themes/Modern Lines/ExtraLarge and /Applications/Aperture.app/Contents/Resources/Book Themes/Photo Essay/ExtraLarge I found that adding the two lines
also for the "Modern Lines" Theme.plist I was able to add map boxes.
Hope that helps!
One option is to create a new book with the images you wish to use on a map and then using the photo journal / photo essay theme create the map based on your requirements. Once laid out use file>print>save as pdf to create a pdf version of just the map page of the book. Import this pdf (which is effectively an image) back into Aperture and use in your book theme that does not support maps.
An alternative is to create the map in iPhoto or an image editing app. I have previosuly used slides from keynote with images & bullet points sucessfully in a book orderd form Apple.