The first thing you'll need is a place to do the cooking. You can run out and spend $1000 or so on a good high quality smoker or you can put one together in the backyard. Depending on how industrious you feel, you could buy some plans or you could rig one up.
Pit Building: One way of building a pig cooker is to get some 8 inch stone blocks a few metal rods and a wire screen. Build a rectangle with the blocks so it's inside measurements are about 42" wide 50" long and 18" deep. Set the metal rods on top of the blocks to support the hog and place the wire screen over the rods. Then you can place the hog right on top and let it cook.
Preparing the Pig Once you know how and where you are going to cook the hog you need to get the pig. Try to find a skinned and trimmed carcass around 60 to 100 pounds. You want it to be lean so that you don't start any grease fires. The carcass should be butterflied so it can lay it out relatively flat. To get a whole hog, call around to some local butchers and see if they can help you out. If you can refrigerator a whole hog get it a day in advance and season it up with a good rub then let if sit for a good day. If you don't have a place to store it then get everything ready so you can get the hog on the fire as soon as you get it home. Season it as you cook.
Building the Fire: Now you're ready to build a fire. If using charcoal briquettes, you need about 60 pounds you can also use hard wood logs burned down to coals. If you have a fancy professional smoker, follow the instructions on building a fire. If you are using a backyard pit, I suggest building a fire ring next to the pit so you can build up the fire there and then move the coals to the pit. Keep adding coals to the pit throughout the day. Start with about 20 pounds of coals. Load them all along the bottom of the pit with more coals on the ends under the hams and the shoulders so the hog will cook evenly.
Cooking: The plan is to cook the hog for about 10 hours. Start in the morning. Build up the heat throughout the day and watch the temperature carefully. Use a good meat thermometer placed deep into one of the hams. When you hit about 170 degrees F. (no less) the hog is done. Cook skin side up for 4-8 hours and then flip. Cook an additional 1-2 hours and turn again. Finish cooking skin side up. Make up a good mop and baste the hog about every hour or so. Apply whatever sauce you want at the end.
Pulling: Once the pig is cooked remove it from the fire and let it sit for about an hour, wrapped up tightly. This will let it cool down a bit, but also let the heat even out and the juices flow back into the meat. Now you are ready to start pulling the meat. The meat should pull freely from the bones. You should start by cutting or breaking the pig up into large pieces about 5 to 10 pounds each. From these large sections shred the meat into small pieces or strips. You do not want to crush the meat, but gently pull it apart. A good pair of insulative, latex cooking gloves are a must. Put the shredded meat into a large pot to keep warm and to mix up. A perfect pile of pulled pork should have meat from every part of the pig.
Watch the fire and the hog carefully. Invite a lot of good friends over and you'll have yourself a good old pig pickin'.