Grind the annatto seeds, cumin, peppercorns, allspice and cloves finely in a spice grinder.
Seed and finely chop the habanero, and blend smooth with an immersion blender together with the orange juice, vinegar, salt, garlic and the spice powder from the previous step.
Stir in the lemon juice and tequila.
Put the pork in a large resealable plastic bag or bowl, pour the marinade over it, and turn to coat evenly.
Marinate in the refrigerator for at least 8 hours, ideally 24, turning occasionally.
Preheat the oven to 160 degrees. Put the meat with the marinade in a baking pan lined with banana leaf (or aluminum foil), and wrap it airtight so the steam cannot escape.
Roast for 4 hours - the meat should fall apart with a fork.
Carefully unwrap it, shred the meat with a fork, toss it in the remaining juices, and serve with rice or in tortillas.