Found this while looking for something else for you that I used years ago before getting my theory down. (Chordspace or something?)
http://www.synleor.com/improvisator.html I know my theory pretty well by now, but I'd be damned if this isn't the best thing since sliced bread.
Currently just playing around with it, seems to work fine in Sonar.
There's a demo you can download to check out.