It's very simple, you just wire up some potentiometers to the correct pins on the controller ports. Both joy ports have 2 potentiometers (I think they're supposed to be 500KΩ each?), X and Y.  If you want to be a bit fancy, you can combine a potentiometer with some other components (caps, trimpot, resistors) to make a much nicer, linear effect with can be calibrated for zero deadzone:

http://chipmusic.org/forums/topic/4630/ … w-circuit/

For added fun, you can add a switching potentiometer that either grounds the audio in pin (it's left floating for some stupid reason and adds a shitload of noise as a result) or allows you to feed the audio output back into the audio input (through the potentiometer) to get a variable feedback effect. Which sounds really cool.

Ugh. I would so want this, but the euro prices would brake my bank :'( Some top quality stuff Akira does, though. One day... one day...

I am interested in how this mod was achieved @ akira^8GB. This is an awesome mod for the C64C Since I want to do some chiptune something like this is right up my alley

A shot in the dark here:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? … 0838789611