If you get a chance, check out the texas boars site. Those guys do this all the time and are real experts on this. I will do one of these someday, but I think I should do at least 1 more handgun or bow hunt as prep.
Basically dogs run out into fields. If hunter/guide has an atv, they follow on that - if not they run after dogs. If dogs catch wind of hog, they chase hog. Again, if hunter/guide has an atv, they follow on that - if hot they run. At some point the hog usually decides it's had enough of this running crap, or gets corner and then turns to fight the dogs. The dogs circle it at which point 2 of the older, better trained dogs move in to grab the ears of the hog (I think they're called "holders" - I could be wrong). The hunter then moves in to either make a thrust behind the shoulder into the vitals (being carefull not to hurt the dogs), or I've heard of some cutting the neck. I don't know which is more effective. That's kind of how it's supposed to go down.
As an aside note, when humans hunt animals we make an effort to be as humane as possible. When you are using dogs, they are animals - they have no humanity and are in no way "humane". You gotta be ready for the natural violence that occurs when a dog is hunting the way a dog does. There's not a single thing wrong with it - it's animals hunting the way nature intended, but we are so disconnected with the realities of the natural world in our daily life that the truth of it can upset our urban sensibilities.
Tim