Preheat oven to 300 deg. Check oven with oven thermometer to make sure it is accurate.
Score the fat on the pork diagonally with a sharp knife in a crosshatch pattern, With a small paring knife, make a dozen 1/2 inch deep cuts in the top and sides of the roast.
Place the garlic, onion, jalapeno and oregano in a food processor and process until the ingredients are finely chopped. Add the cumin, chile powder, 1 tbl salt and 1 1/2 tsp pepper and process for 30 seconds to make a paste. Add the vinegar and olive oil and process to incorporate.
Rub the mixture all over the pork, including sides and bottom. At this point, you can refrigerate the roast, for up to 24 hours.
Place roast in a large roasting pan, fat side up.
Pour 2 cups of the wine into the pan and cover the whole roasting pan tightly with aluminum foil.
Roast for 2 1/2 hours; remove foil and roast for another 4 to 4 1/2 hours, until the pork is very, very tender when tested with a carving fork. Every 2 hours, add another cup of wine to keep some liquid in the pan.
Remove the pan from the oven, cover it tightly with aluminum foil, and allow the meat to rest for 15 to 20 minutes. Slice, sprinkle with salt, and serve with lime wedges.