Walk, walk, walk, and more walking. He needs to be moving. When Rascal coliced the last time I lost 15lbs walking. Days and days of walking. Walk a half hour, rest an hour, walk another half hour, rest an hour, walk for an hour, rest for 2....on and on. It worked though :) he is still with me.
Not necessairly... Walking doesn't do anything but wear you and your horse out. It's just important that your horse doesn't roll and walking helps with that.