Apparently nothing. No one does it. This is not really surprising. Here are some quotes from an article in the chronicle:
“Meanwhile, several projects aimed at helping MOOC students navigate existing pathways to college credit have attracted little or no interest. Colorado State University-Global Campus has seen no takers since offering last fall to award credit to students who performed well in a computer-science MOOC offered through Udacity. Likewise, the Council for Adult and Experiential Learning, which helps students translate nontraditional learning into college credit through its LearningCounts program, has not seen any students attempt to redeem MOOC certificates for credit.”