= Update =
It is a better idea to have the ATX set up in a box and to use the ATX connector to connect to the banana plugs. Basically, it is then possible to have the 5 usual plugs (GND, +3.3, +5, +12, -12) and add a regulated output (0-12V). The visualization for that regulated output can be analogical. That would be great to have a current limiter on that regulated output also.
It might be possible to use a LM317 for the voltage control.
We can use an ATX 24-pin connecor adapter to connect the PSU: http://tinyurl.com/6bza3o7