How to do this...

[hatembr]

anyone can explain how is this thing -Keith Hillebrandt is talking about- can be achieved?

[...]a lot of strange, evolving drones and a lot of envelope-triggered loops, which were basically noises that I ran through my [ARP] 2600 and then had the envelopes triggered by drum loops. That would create strange peaks and valleys, kind of giving you the feel of drum loops but it didn't sound anything like your standard off-the-shelf CD_ROM drum loops.[...]

taken from here:
http://www.9inchnails.net/remix-files/keyboard_mag.htm