Tortillas, cilantro, avocado, limes, etc. for serving
Place the pork shoulder in the slow cooker. Rub with olive oil and sprinkle with salt, pepper, oregano, cumin, chili powder, and cayenne pepper. Add the garlic, onion, and jalapeno to the slow cooker. Pour the lime juice, orange juice, and salsa into the slow cooker. Cover and cook on low for 6-8 hours, or until tender.
Shred the meat with two forks and return to slow cooker to combine with the leftover sauce inside.
Preheat the broiler. Line a baking sheet with foil and spread the meat evenly over the sheet. Pour some of the sauce over the meat. Broil for 5 to 10 minutes, or until the edges of the pork are browned.