TIP: Soak your pinto beans overnight before you begin. (This makes them less "gassy" and softens them up so they cook in less time.) The next morning, sort through and make sure there are no tiny stones in the mix before you cook them. I always find at least one!
Put all ingredients in the slow cooker and cover with water
Cook on low for 8 hours, or high for 5-6 hours
About an hour before it's done, shred the pork and return to the crock pot
Serve in tortillas - with the usual toppings. NOTE - if it is a little soupy, that's normal. I usually spoon mine out with a slotted spoon so they're not too drippy in the tortillas.