6 Axis limits your choice of controllers, but the big question is, how are your amps/servos controlled?
Step/dir, CW/CCW, or +/-10V?

For something like this, I'd suggest a KFlop. You would have to write some C programs to configure the KFlop for your machine (plenty examples are given), and if you wanted KMotionCNC to natively handle the kinematics for all your axes, you need to re-compile the KMotion kinematics library with the correct values for your machine (there was mention of this being changed so you don't need to recompile it, but I'm not sure how that's progressing).