Unroll the sausage casings and soak them in cold water for an hour or so. Pull them open and run water through the casing for a few seconds. Keep moist.
In a stockpot or kettle, combine all the stock ingredients with enough water to cover (at least a gallon of water). Bring the stock to a light boil and cook uncovered for two hours. Skim the fat and scum off the surface as it cooks.
Slice the pork liver about a half-inch thick. Fry the bacon in a large skillet until crisp. Remove the bacon and eat it (or save it for a sandwich or a salad). Add the pork liver and all the other liver preparation ingredients to the drippings and sauté over medium heat until the liver is tender. Remove about a half-cup of the stock from the stockpot and add to the liver pan. Bring to a simmer and cook another ten minutes. Remove from the heat and cool, then refrigerate.
After the stock has cooked for two hours, remove the meat from the stockpot and set aside. Strain the stock and discard all the vegetables. Return the stock to a light boil and reduce to two or three quarts.
Reserve two of the chicken leg quarters for another purpose. Skin the other two and dice the meat off the bones. Also dice the pork shoulder, cutting across the grain of the meat. Refrigerate all this when finished.
When the stock is reduced, pour five cups into a saucepan and add the rice to that saucepan. (Remove the rest of the stock from the heat.) Cover the saucepan, lower the heat, then simmer for 25 minutes, until the rice is very tender and borderline gummy. Fluff and set aside.
If you have a meat grinder, fit it with the coarse blade or quarter-inch die. Combine the diced chicken, pork, and liver. Run that through the grinder once. If you don't have a grinder, a food processor also works, but stop short of mincing the ingredients.
Combine the ground meat mixture with the rice, chopped parsley, green onions, and the black pepper. Add 1 to 2 cups of the stock, a little at a time, and mix to distribute all the ingredients evenly. You have enough stock when you can easily make a ball of the ingredients without its sticking to your fingers. Add more cayenne and salt to taste.
At this point, you can either stuff the boudin into the casings, or you can make boudin balls without casings. Either way, microwave to quite warm before serving.