I don't believe that is supported in HTML5/browsers.
The gamepad support is hardly working already, let alone for "older" controllers like MIDI keyboards.
Maybe later, with a USB midi keyboard, hoping the gamepad support would be wider and would support pretty much any type of controller, maybe it could be possible.
It might also require a specific plugin for C2 though, hard to say.
For now though, I believe it's just out of the picture.