I am drawing a machine part which has a cylinder whose axis is not perpendicular to any particular face.  Picture a canted valve cylinder head.  The angle of the axis can be specified against two perpendicular planes, but the position of the pierce point of the axis must still be described. 

I am having trouble figuring out how to do this.  I have place a reference point at the point of intersection, but can't figure out how to select this in a drawing.  Has anyone solved this before?

Thanks,

Alan