by Miguel Santos.
Hi Jarrod,
This sounds like you would have to do some custom code to allow your WP site to access moodle's code. I would suggest start looking in enrol/paypal and check out what data is required (enrol.html) and then look at how paypal returns data back to moodle (ipn.php). I would guess you would want to have the links to your course enrollments be generated by pulling info from moodle and likewise generating the urls with the course info.
Hope that helps get you started.