Here, this is from another forum that I had posted on a while ago. Might be useful over here for some people too.
For PTO @ 1200rpm its a yellow/green wire. You just use a butt-splice and hook that wire to which ever upfitter you decide to use. Start the engine, parking brake applied, trans in park, and flip the upfitter. The engine will smoothly climb to the 1200rpm. It will NOT regen in PTO mode, or so the Ford document had stated.
You pull off that panel below the steering wheel... the upfitter bundle and the add-on bundle are to the far left, above the parking brake mount, about 3 inches apart. Here is a pic. I have both SEIC and BCP, just to try them both out.
PTO (the yellow/green wire), will idle to 1200rpm, but there is another wire you can add a resistor or potentiometer to, to change the "PTO" idle speed (all the way to 2400rpm). BCP is the purple/brown wire, and will hang at 900rpm and idle up from there depending on electrical load, (hence "BCP", Battery Charge Protect).
Here is the pic...