Cubase should have a 'legend' or something about what control changes in MIDI will control what parameters in Cubase...
Once you find this out you merely program the knob, button, or slider to coincide with that control number..
I did this on my Pro88 from M-Audio... It was a pain in the butt initially... But, Once I was finished I was tickled to death because the controls work so well!!!
Hope this helps...