Is there any way to insert points by giving their x,y,z coordinates?  The insert curve will take points but I can't find a way to let me define straight segments with a specified radius of curvature for each turn, just a continuous spline.  The only thing I can find is to add a point in a sketch (which is 2D on each plane).  Add a referece point has no option to define a location so is also unsable.