How about this? Buy the A/B/C switch from RadShack, take out the guts and the parts that you need, and put it in something smaller, heck, even a tupperware container would work great if it was hidden under the seat. I think it would still be better to make it yourself, and you would have something to brag about and show off along with your 3l33t empeg - more of a "I did it" custom job. If you find yourself with a whole lot of parts and no idea how to put them together, you could always run to RadShack and buy that switch that Dearing mentioned (how much was that, by the way?) and wire yours similarly. You would have *tremendous* amounts of freedom with the exact setup if you were to make it yourself, even with very rudimentary electronics skills, and I'll bet you could make it look *very* slick making it yourself for your Ford.

How about buying that prefab box from RadShack, buying a 2-way switch to replace the one that comes with it, and then getting any other minor parts you need to finish your box? That way, you'd have the knowledge of how a working one was wired, and it shouldn't be much of a problem at all to simplify that for your needs. Geez, you could even just buy the 3-way from RadShack, and then buy some other neat audio gadget to use up that last set of inputs! That way, you've got the magic word: (insert reverent tones) EXPANDABILITY!!

Festus