I just picked up a used MHO mill with a Servo II controller on it. It came with a PC that was fried, and the software dongle. I was able to get the software from ServoSource. It is DOS based. I saw something in another thread on this forum that seemed to suggest they give the DOS version of the software away for free. They want like $2k for the windows version, so I thought I would just stick with DOS.
It uses an RS-232 cable to communicate with the controller. So, all you need is a serial cable, a PC loaded with DOS, and the software and you should be good to go.
Hope this helps,