i've roasted a pig on a spit every year for the past 13 years or so at my old friend's birthday party. we've also done lambs, but pigs are more popular.
i usually pick up a 100 to 125 pound dressed pig, and it is cooked for 10 to 12 hours, turning very slowly over a mix of lump hardwood and briquette charcoal.
another friend, a welder, built the spit and charcoal "table" and connected a low rpm motor and a bicycle chain/sprocket to the spit. once the pig is up, it's just a matter of continually mopping the beast. (and fending off prematurely hungry guests and their kids; and even their dogs!)
our favourite mop sauce is a mix of honey, bbq sauce, and gulden's spicy brown mustard.
btw, drama queen, killing and cleaning a 225 lb. pig ain't no easy task!
we decided to "do it the right way" one year, and got a live 125 lb. pig.
the farmer said to just hold him down, and give him a good whack on the skull with a 10 lb sledge. it seemed a little barbaric, but you can't use firearms in city limits, and no one wanted to use their chain saw, so we gave it a try. (if our welder buddy was available, we wanted to get him to make a guillotine).
15 or 20 blows later, the pig finally stopped screaming. we all had nightmares for weeks after that.