4th axis settings

[whiteriver]

Ok I am putting together a 4th axis for my router table. I had a spare Nema 42 2600oz-in motor and a 40 to 1?? rotary table laying around. Also had a spare gecko 201 microstepping drive. I built the frame for the motor and rotary. I bought the timming gears (still have to bore them out tommorow on the lathe) and timing belt. Got the drive set up to my A axis and it turns the motor.
My question is how do I set up the steps per unit. Its a micro stepping drive and maybe a 40 to 1 turntable. I think the motor resolution is 0.00025". The timming pulllys are the exact same size. No gear reduction there. And what the unit? 1 rev 1" , 1 deg?? And what do I tell my cam softwares post code? Anything special?

Thanks in advance.