My bad, I read the post when I first woke up #brainfog.
Safest way to control the knobs on PO is with a vactrol, see this basic (and crap) schematic. Note, I might have the PO pots ground and +V transposed.
(Please excuse the crappness, drew it on ipad, need to get a decent tech drawing app, or some paper 
)
Here are the S-Trig settings I use, note the 0.1v setting may not be necessary on some gear, it depends on the circuit.
