Dusting out the inside of my computer this morning, it occurred to me that the line-in port of the sound card is a 2 channel analog input, which with the right interface hardware and software could accommodate an analog stick. Since the port doesn't respond to DC levels, It'll necessary to use an AC tone, which introduces to possability of more channels encoded as different tones, pealed off in software. Funneling the decoded data into a stream that most game software recognises threatens to be the hardest part on a certain OS.