If you command a move of 1 inch and it moves 5 inches then change the steps per mm on that axis to 1/5 of what it is set for currently. So for your x and y you would need 250/5 = 50 steps/mm

Likewise on z you command 1 inch and get 3.1875" movement then 250/3.1875 = 78.431 steps/mm

As for what else to configure that depends on what your CNC has. You can add limit switches, a probe, connect spindle control, etc. What kind of machine do you have? Any pictures?