I've only ever used the Servo Ready, and Fault DOs, however the only one you probably really need is the Fault output (or possibly just the Ready output, as if you lose that signal, the drive has either lost power or faulted), wired in just like you would a stepper drive.

What you use really depends on how much functionality you want in the controller.
You could wire/program servos so you can reset them in software should a fault occur (not all faults can be reset without a power cycle), you can monitor individual drives for faults, you can monitor that each drive is ready, you can trigger a fast/emergency stop in the servo.
However what you implement really depends on the controller (with an AXBB, you have limited inputs, so you probably only want to monitor the essentials), and the size/complexity of the machine.