well, you would use the photon output to drive a power transister to deliver the high imput to the arc.
The best way to do this would be to find out what chip the arc folks are using and connect the photon output to the blanking line on it. Most of the chips that these guys are using have an on/off line into the chip that is designed for use with separate PWM circuit to provide dimming.
You might be brave enough to try things
It will either be not connected to anything, or it will be tied high through a resister to V+. If you examine the sample schematics you'll see it there.
That way you would only need the photon circuit to provide the logical ON voltage to the arc circuit, and the real operating current would still be using the regular lines.
Course, you might want to build all that yourself. Or talk to Wayne, I'm sure that he would build you a BB500 with the PWM control line brought out somehwere you could easily solder to
Oh, what fun all of this is!