Watch the Buckshot online guitar lesson by Shane Theriot from Rhythm Mojo
Tuning the high E down to D gives us an instant tension in a good way. I use my thumb (remember Funky Thumbs?) and some fretting hand mutes to make the riff work. It's actually a very simple idea, but to make it feel right it takes a combination of all of the above concepts. Pay attention to the way that I add the triads in there. The B section is an example of how just doubling a bass line (unison) can be a powerful touch. The neat thing about the alternate tuning is that you can get some new life out of familiar voicings.