Are we talking FR-1X (piano) or FR-18 (diatonic)?
http://www.youtube.com/watch?v=kguWIOg6VQshttp://www.youtube.com/watch?v=sqcTlv9_mBgThe stops on cajun accordions are really reed cancel switches. When open the reeds sound, when closed the reeds do not sound.
http://www.youtube.com/watch?NR=1&v=rBHCMmfGTOA&feature=fvwpThere are no stops on the Roland as seen on the Cajun accordion. There are registers where you can change the voice and tone and duplicate a zydaco or Cajun accordion sound, but one really can't emulate the particular nuances of a diatonic from a non diatonic keyboard. IMO, you can come close, but there is a difference.
This guy is not bad.
http://www.youtube.com/watch?v=NTGE-_AU5sM