brooklyn - I'm pretty sure I bought this pot at Radio Shack....they sell 100k linear ones with a long shaft. I didn't even have to cut it off to fit; it extends all the way to the side wall of the pedal. But you can easily cut them to length. Can't remember if I had to do any other fitting, but looking in the pedal it looks like it went right in. Yes, I did it myself. As mentioned, look online for instructions on replacing the string, it has good photos on how the string gets wrapped, and is important (or take good notes and draw pictures of the wrapping). If you do it yourself, pay close attention to the string routing. And getting it hooked on the spring is tricky, I used long needle-nosed pliers.
ronandc - all a pedal needs is an appropriate potentiometer with a 3-wire output to the softstep, either via a cable with male jack on it that plugs directly to the ss, or a female jack attached to the pedal. Essentially all you need to do to redo most pedals is 1) if the pedal just has a mono jack/output, rewire the existing pot with 3-wires (see earlier message on where wires go), 2) test it with softstep (reverse your wiring if you have backward operation, see earlier message), 3) if it works you're done, 4) if it doesn't work, find a 100k pot that will fit/replace the existing one, and wire it up. Other ratings may work, but the 100k calibrated nicely for me.