In a large sauce pan, combine the pork butt, pork liver, water, onions, garlic, bell peppers, celery, 1 teaspoon salt, 1/4 teaspoon cayenne, and 1/4 teaspoon black pepper. Bring the liquid up to a boil and reduce to a simmer. Simmer for 1 1/2 hours, or until the pork and liver are tender. Remove from the heat and drain, reserving 1 1/2 cups of the broth. Using a meat grinder with a 1/4-inch die, grind the pork mixture, 1/2 cup of the parsley and 1/2 cup of the green onions together.

Turn the mixture into a mixing bowl. Stir in the rice, remaining salt, cayenne, black pepper, parsley, and green onions. Add the broth, 1/2 cup at a time, and mix thoroughly. Either using a feeding tube or a funnel, stuff the sausage into the casings and make 3-inch links. Bring 1 gallon of salted water up to a boil. Poach the sausage for about 5 minutes, or until the sausage is firm to the touch and plump. Remove from the water and allow to cool slightly before serving.