Michelle,
That is very achievable. In fact, a couple years ago, I extended the functionality of the Learning Journal to include both checkboxes and Madlibs. Here is the version that includes both those features. Simply search for the word "checkbox" to see all the code in the file related to the checkboxes. If the "Part" field is set to 1, the checkbox is clickable. But later in the course if the same ID is used but the "Part" field is set to 2, the checkbox is read-only, allowing you to display all the checkbox results at the end. Warning: this is from a stale, 2-year-old branch of the Learning Journal and therefore simply replacing your LearningJournal.js file with this file will fail. But it's a good start.
Mike