You know, the actual 'hum' part of the album. I'm not sure what he's using to generate such low frequencies but it reminds me of Info Dump somewhat. Anybody have an idea?

It's fairly easy for an intermediate producer to replicate and understand how to make sounds like that, but to explain it, that's almost a different story. It's all really just the art of sound manipulation and visualizing the "outcome" of the sound in your head as you go along. One way to simulate a droning like in The Hummer is to record fuzz or feedback from your guitar, tweak the EQ, lower the pitch and loop the wave repeatedly. Another way is to use VST plugins, such as KORG, and manipulate that. The possibilities are endless, really. As for the actual method Townsend uses, who knows? It could be a loop of his own voice with an extremely dropped pitch for all we know.