Well other than swapping out the Stepper Drives for Servo units, you would likely need to also install a Belt Drive between your Servo Motors and the Ball Screws? Most of the Servo installations I have seen (non Tormach) are DC Brushed Servos with a Belt Drive reduction. This could depend on the type of Servo Motor you plan to use. The higher end machines that are using Brushless A/C Motors tend to be direct drive. The Power Supply would also likely need replacing to match the voltage of your new Servo Motors? Hope this has been some help.