I bought one, as mentioned a couple of years ago in this thread. I used it as an arranger for about a year. I controlled it with an Edirol keyboard controller. The Edirol had 50 programmable buttons to call up virtually anything on the module, even things that cannot be addressed from the module itself, only through midi.
Unless you are just using midi files or MP3s, you would have to have some way to input the chord information, either a keyboard, accordion, or midi guitar.
It's fairly easy to used the module itself to control Variations, Sounds, Performance. MUCH more can be done using an external controller.