Ok, I tried the ATX solution... here is what I found.
To turn on an ATX power Supply you must short pin 14 (PS_ON) with any black (COM) wire
To KEEP it on you need to short Pin 8 (PWR_OK) with any red (+5VDC) wire.
NOTE: Apparently the Power_OK pin checks to see if a load is present and keeps the PSU alive. This may only be needed on newer PSUs
Good Luck!