We've gotten on several. The "ground-roasted" were the best.
A (Hawaiian) friend of the family does it like so:
Get one crew to prep the hog; scraped or skinned, but skinned goes and cooks faster. Belly cavity is filled with onions, or your favorite herb and sewed, wired, or hog-ringed shut.
The other crew preps the "gravesite" by digging about 4' deep, laying rip-rap around bottom and sides, then kindling a fire which they keep going all day. By about 4:00 A.M. they lay the hog corpse to rest (by having wrapped him in cabbage leaves, -since banana trees are in short supply in the Midwest-; after the cabbage leaves comes the chicken wire to hold him all together, and is easier to do if the chicken wire is layed out with cabbage leaves, hog applied, and rolled up. Then comes the wet burlap; about three layers.)
Then the coals are pushed aside, hog buried in coals, coals buried in dirt, dirt covered with a tarp, and everyone goes off to take a nap till around noon. The ones I helped on were 150-200 lb.
Then the corpse is exhumed. (It's hot in that there grave!) Then the wire cage is pulled up and any remaining ashes brushed off. Then with a big container handy and the end cut out of the wire cage, the whole thing is dropped; bones, meat , and herbs falling apart in one big pile of gluttany. At that point, its ready for the human hogs to take over.