Hi Paul, I haven't experimented with the little circuit board that you show in your picture, but from what I can find on the internet it looks like it is intended to be used as "driving smoke" and not "barrel smoke." I suspect it wants you to attach the servo cable to your throttle channel, and smoke will be created as a function of your driving speed.
As Chris says you could try connecting the servo cable to the recoil servo output of the TCB. Maybe it will work or maybe not.
But what is guaranteed to work is the relay method described in the Wiki. You won't need the circuit that came with your smoker, but you can still use the air pump and the smoke box, just wire them as explained in the Wiki.