This is one of my favorite basslines of all time. It's clearly a soft synth or synth playing the line- I just need some help deciphering what sort of synth waveforms/combination of sounds would get closest to it. The line start a couple seconds in: http://www.youtube.com/watch?v=CybO7XtYpdU#t=00m45s
Sounds like a sawtooth with maybe a light resonant LPF to me. Foot sweep would probably work, but an envelope follower could aid in funkiness if you have something with a side chain/key input on it.