Hi!
Sorry if this email comes twice, but for me it seems that my emails don't come through.
I designed such a device and built it into my Kawai K3m and Casio CZ101.
Also the Poly61 and Polysix, Poly800 should be no problem.
Every device that works with 3.3V or 5V on the keyboard should work as I switch analog switches (controlled by the software in a little uC) in parallel to the built in buttons.
You can find information here:
http://synpro.heimat.eu/datadial.htm Ciao
Peter
http://www.ullrich.at.tt