I put a pot on the kbcc dc spindle control p1, p2, p3, connectors (the same terminals that I had the Digispeed connected to), and found that the kbcc wasn't tuned at all for my motor, so I am working on that at the moment.
Once I get the motor running well with the kbcc using the pot, I will get back to the Mach3/Ncpod/Digispeed control interface. So far I have control of the motor speed with the pot, but I only am using about a tenth of the full clockwise rotation, so it is very sensitive.