Jack...

Go hit my web page:

http://www.iag.net/~mv338

Once there hit the XP-50 Files link at the top and there you will find the answer that you seek...

In short, you have to create a blank performance on your XP-50 and call it Cakewalk...Assign each PART to an individual midi channel (ie 1-16)...Open a 16 Multi-Channel Template in Cakewalk...Now you should be able to Change your respective parts from Cakewalk using the instrument def file. The TEXT file on my page is more descriptive....