hi gen, most sound parameters can be changed thru midi, BUT only thru sysex messages..if you want to do this in a live(realtime) situation you could use something like the excellent Phatboy, or the Behringer control surfaces which will allow realtime editing of dco's lfo's tracking, octave changing etc etc etc..just plug em into the midi in....they have for the most part a small "footprint" son can be placed directly on your keyboard...the other way is to program sysex into your midi files so it changes thru the song..but you need to ensure you reset the parameters for your next song....hope thats of use
dennis