Rear-Wheel-Steering: Myth or Miracle?

[PDSides]

Anybody here an expert on rear-wheel-steering as rumored on JDM SVXs? I am wondering how complicated an active rws system has to be in order to be workable and practical. Was the JDM rws system active or passive, and if it was active, how was it powered and how did the system work? I may have posted this in the wrong section but wanted to scare up an expert if one exists on this forum. Thanks.
Preston
PS - I once had a swing-axle Corvair that essentially had passive rws that kicked in at just the wrong moment.