I'm developing an editor for the MU128 and a download is available from www.robotsoftware.co.uk/comingsoon.htm. Its still in development so this message is to get some feedback and some beta-testing. Its still usable at the moment. Some features are disabled and only works for 16 parts at present. Should be complete in a few months.

It uses Midishare as a driver so you may want to check out the www.grame.fr/midishare if you experience midi problems and conflicts.