set up cakewalk to reiceve midi. Sync your mpc4000 to cakewalk and you can either record straight to cakewalk or record to 4000 and then either play it back and have cakewalk record the midi in data, or you can just save it, load it into cakewalk do your editing, etc. save to midi format 1 and then load it back to the 4000. there are many ways to do it.