I'm just curious whether this can possibly be done.
Not being an expert on what sort of electronic components exist...
Would it be possible to create a simple circuit that would control the up/down buttons by a knob? I just have this rough idea of one of those infinite "pots" hooked up to an IC that would send out a signal replicating the button presses?
[[I suppose I generally think too straightforward on my mods. A year or so ago, I programmed a gameboy synth, and controlled it with a keyboard wired up to the buttons on the GB. It had three octives and each key just pressed the right combination of buttons that I'd programmed as this crazy matrix in Assembly... There would have been a much easier way to do it using the serial interface inside the cartridge, but I didn't get that far in my studies.]]
Also, I very vaguely remember the HAWK mod(s) being able to possibly do this with the joystick, though it'd obviously be doing through different means. Is this correct?