Listening to the track, I'll second what BusterDog said. If you listen closely, you can hear what sounds like a train in the background, it's the bassist slapping the upright.
www.bassplayer.tv has an interview with Lee Rocker and he shows some upright slap techniques, you can hear what I mean when he slaps triplets.
That would be tricky to mimic exactly on an electric, but you might be able to do it using a pick and tweaking the sound a bit.