While I'm not overly competent with CiviCRM I recently needed to work on the content of a page from within a drupal module. The hook system seems to be in active development but as of v2.1.2 it hasn't got to the point of exposing the template to the hook api. I added a few lines of code to enable this. I also files a feature request for version 2.2 so hopefully it'll be added for that.