Not sure where your reaction to other posts came from, maybe they were former Atari ST users?
About the hardware at hand, yes it requires an external power supply, much like the GVP gear that went on the side of A500's did, but with a strange connector. I have one and can measure the voltages on the pins tonight. I doubt you will be able to find the required plug, but there is always the ugly and dangerous hardware direct hack.
