weird, i was thinking about this last night, for Barely Awake's old bike. sorry, don't have any ideas right now besides hitting up Jim at Creative Engineering. i'll get back to you if i come up with anything...
Not sure if it can be done or if the hub is the right size but the moped hub I'm going to use in a build has six holes drilled between the spoke holes on the hub. Granted this was made to have a sprocket installed (standoffs for the sprocket and a shoulder) but it doesn't look like it would be very difficult to do to any sprocket that's the right diameter.