What did you have to do to get credit? Did you have to have a teacher supervise your work? Any suggestions you can give out?
I just reposted an article that our friend Steve Levicoff wrote quite some time ago detailing the entire portfolio process at Thomas Edison. (It would be virtually the same at Charter Oak or Excelsior) That should answer a lot of your questions. If it doesn't, feel free to ask additional questions here.
More specifically, what can I do to prove knowledge of a course equivalent to the "History of Guam?" Without using a teacher.