I think this could be very interesting, but I would not know a solution in real time as you have to convert your music (or rather elements of your music) to a SVG file (it can't read jpg or png, your plotter needs a discrete vector format says the manual). So you can't just let the plotter do stuff while you jam with your gear. The plotter needs a closed file in a discrete structure to work. For example a SVG-File needs a header that starts with "svg" and an end of file that is marked with "/svg" . Thats what you can submit to the device .
I own a VCMC by Befaco. With it you could record your modular session and bring elements of your music to MIDI. The VCMC is very versatile in that regard. On your PC I'd say python is the perfect tool for the task as python has libraries that can read MIDI-events and libraries that can create SVG -files (these files are structured like XML files, but specifically for vector graphics).
But with python you could convert whatever information your MIDI file has to whatever element you want in your SVG. A simple task to start would be one note to one strike on paper. Note pitch to y-position and note length to length of this line. But it can really be whatever you want. A quick look at the SVG-documentation shows the huge potiential of shapes you can get.
This sure needs some research and developement but I'd say it could look super rad. But i am afraid you'd need at least basic programming skills for that. And it could take quite some time to get nice results. Thats a really nice plotter you have there. :)