I would have to see the actual template code/html to try to explain
how to do that. Generally the easiest thing to do when you are unsure
is to make the changes in the app then use campaignTemplateContent()
to see how the section is named and pass it back through via
campaignUpdate(). There may, however, be certain types of content that
won't work well, and something named that may fall into that category.
http://www.mailchimp.com/api/1.3/campaigntemplatecontent.func.php
jesse