Yes, if the organ program is in a multi, go to the Control section and set your sustain pedal to CC29 with ON value set to 127 and OFF set to 0. Otherwise, edit the organ program itself: go to the Params page, highlight anything in the left column, then hold the ENTER button and press the Variation button. Once it jumps to the speed parameter, highlight the word Variation, then hold the ENTER button and step on your sustain pedal to reassign it. Test it out. If you like it, save it as a new program.