you can download a midi bass line from here: http://electrofresh.com or download any midi file and mute all the tracks but the bass track then you can dowload some inst bass programs from here: http://yoursampler.com and you are ready
make a bass tone with a single cycle from a sample or draw a sine, triangle and square wave in a wave editor. turn loop on, set it to note on, ans set the delay to your liking. then turn 16 levels/tune on.