that's studio wizardry at work ... but you can fake it live, if you use a high gain pedal with a parametric EQ, boost the mids until it sounds nasal, cut off all the bass and treble, use enough gain but not too much or you'd like GI sheets being rubbed together.
when the band kick in, just use your normal distortion setting. the only downside is that you have to have good distortion pedals. my cousin does the effect with a zim foxrox.
