Make sure you have lots of beer.....dig a pit, start a fire with some hard wood, get that thing really hot and burn lots of wood, make sure you have a good bed of hot coals. Throw in some river rocks....lots of them (be careful for exploding rock)...when the rocks are hot and the coals are completely out you are ready to add the pig.
The pig....Season with your favorite rub, inject with our favorite injectable maranade, that is up to you. Wrap in Banana leaves (we use green leaf lettuce cuz there are no banana trees in Montana) wrap in a wet burlap sack, then wrap in some chicken wire and wire shut to keep things together. Place in the pit of hot rocks and no red hot coals, cover with dirt, cover pit with a blue tarp, cover tarp with more dirt. Now somebody watch the pit for escaping steam, cover escape holes with dirt, drink beer, sleep, take turns watching and drinking beer. The pig should be in the ground and covered at about 4:00am the morning of the feast, that way you have about 12-14 hours of cook time.
That is how I cook a pig in the ground....