http://www.lab4.com/weaponry.php

There's a bit about it there.

Another trick that we often use to create riffs is to program a pattern of Midi volume controls that go from a full vol of 127 to 0 and back to 127 in a way that you can then hold down a chord and it will be chopped up into a riff perfectly in time regardless of how 'in time' we may have played the chord - the volume info is being sent out perfectly in time so the riff will be in time. Some good examples of this are the riffs in 'I'm alive', 'F8' and 'Candyman'.
Sounds like the filters a hi pass distorted and probably compressed. You could try e-mailing lab 4 and asking as the claim that it's "never been a secret" how they do things...