Ercdave,
I think I can help as I have done this. I was successful in connecting 2 of the CACR-PR servo packs to Mach3. Here is a video if you havnt seen it already. [nomedia="http://www.youtube.com/watch?v=K5TTr84M-jk"]YouTube - Yaskawa Servopack First Run with Mach3 and Smooth Stepper[/nomedia]
First thing I recomend is using a smooth stepper or other pulse generator with mach 3. These AC servos have alot of power and can complete positions very quickly. In order to take full advantage of them, you will need very fast pulses. I had the servos set up for about 2500 steps per inch and was still able to simulate 1300 IPM jobs!!
You will need to wire the alarm reset lines on the servo packs as well as the servo on signal just to get the pack to enable.
They want you to also use a signal out of the servo pack to turn on a contactor that applys or cuts power to the drive when there is a fault.
I will try and find my notes about how I hooked all this up, but im going to be doing it again this weekend so I will be sure to document.
-Adam
www.adambrunette.com - Converting My Harbor Freight X2 And My Jet Jvm-830 Knee Mill, As well as many other projects.