How to use it?

I'll update the built-in help. I don't think a README would be all that useful, as nothing special is required for installation.

In summary: install the module as usual, and enable it and all required submodules under the modules configuration screen at admin/build/modules.

Set permissions to determine which roles will be able to export content.

Once the module is enabled, each book page will display (for authorized users) a link which will generate the request export format.

I hope that this makes sense; if not, please request clarification.