In all honesty, there is nothing special going on there. Its pretty smashed to death. Sounds like Pro Tools at its worst () but its fun and what counts for this style.
Simply put, crank your compression/ limiter to taste to get the trash sound. The harmonies are so distorted is could be done very easily using an antares harmony plug-in no problem. Octave lower than the lead, ... play around with that and you'll be doing cartwheels.
hope that helps.