Id go with the MIDI cable. Otherthing way is (if you want to do it this way...) setting up cubase/logic/acid/nuendo/whatever recording software you have set the tempo to the same the mpc is running(you can even record over a metronome now WOW!

). Now Play your bassline for 1 or 2 bars. Then chop it into quarters(chop at 1.0 1.2 1.3 1.4...) or what you desire and then sample the sliced bits into your mpc. now all you need to do is play your pads every quarter note in the right sequence or you can experiment with changing up the sequence (i.e. playing the bassline in reversed notes..)
Didn't wanna mess up this threads ppl, just thought he might want to know..
pz.Toon