He used little to no outboard gear.
Monitors at whisper like volumes.
Used ambient samples of the kick and snare to achieve size and stabilty from the drums. No reverb on the real kick and snare, but plenty of tiled room and large chamber on the samples.
But as stated above, he would automate every fader. If the cymbals were not being played, they were turned down a little. When hit, he would ride them up. He was conducting the mix, bringing out every last drop of anything to make the songs come alive! The chorus would get a master fader ride to give it more impact. Everything was always heard, and that is not the easiest thing to do. Much attention to detail to make sure if something cool was happening it was heard.