For my graduation engineering project I needed a bench power supply which can deliver ~80W. I used this manual to convert a usual ATX power supply into a bench one. The resulting power supply is outstanding!
If I understood your question correctly, you're not interested in a totally general bench power supply, but just want to make the usual power supply work without actually connecting it to the motherboard, right?
If so, then you should make the following connections:
- Green wire (POWER_ON) to black wire (GND). The PSU will be controlled by the rear switch.
- Brown wire (SENSE) to orange wire (3.3V). If this doesn't work, try a red wire (5V) instead.
As long as your PSU powers some internal circuitry and its outputs are hardwired to some PCB, you may not worry about safety issues or minimal load conditions. In this case you may omit the power resistor which is suggested in the article.
However, if you plan to move the connections and may incidentally touch the outputs (even if the PSU is off), you MUST add the bleeder power resistor as suggested in the article.
P.S. The trick with the fan instead of a bleeder resistor is ingenious!