Submerge the pig's head in water. If you are using dried corn, add it now. If not, wait a while. Bring this to a simmer, and skim off any froth that accumulates. When the froth subsides, add the remaining pozole ingredients and keep the pot at a simmer. If you are using the pork shoulder and feet, it's the same procedure.
If you are using freshly nixtamalized corn or canned hominy, add it after the pork has been simmering for 1 hour. Continue to simmer everything until the meat wants to fall off, or the shoulder meat can be shredded easily. This will take longer for a head than pork shoulder.
If you are using the head, fish it out and strip off all the meat; discard the skull. If it had its tongue, peel that and chop roughly. The rule of thumb with a head is to chop recognizable meat rough, everything else fine. If you are using the shoulder and feet, fish out the feet and discard the bones, then mince everything fine. Regardless, once it's chopped, return all the meat to the pot. OPTIONAL: Once the head is out of the broth, I try to pick out the bay leaves, cloves, allspice berries and peppercorns. This makes the soup easier to eat later, but if you miss a few, it's not a big deal.
Once the meat and corn are tender, you are ready to rock. Lay out all the toppings, and let people mix and match as they like.
NOTE: If you are doing the chicken or other poultry version, you will want the equivalent of 2 chickens, or about 5 to 6 pounds of poultry, plus maybe a pound or two of chicken feet, or 2 pig's feet.