Ok ... I must admit I am stumped ...
UserCoordinateSystems.Add takes 4 parameters, the origin, xAxis normal, yAxis normal, and UCS name ...
Now ... when I am running the sample code on AutoCAD 2000 with a supplied set of points, I am greeted with a new ucs ... however in all other versions I receive an error that the Y axis is not parallel to the Z axis ....
In the sample code the axis is specified by 1,1,0 and -1,1,0 respecively .. this works fine ... but no matter what I do, I cannot create a UCS using a supplied set of points.