USAT has a complete list, but you need to i think come in top 3 at a 70.3 race, or a top placing in a number of certain short course races. it changes a bit year to year.
To get a pro card, you need to finish within a specific % of the overall winners time at a specific number of races which have a min. number of participants as per USAT. It doesn't have to be long course, it can be Olympics or even Sprints.