I had posted a plugin on message 12 of this thread that creates the Homographic (Projective 2d) transformation.
Sadly, the plugin looks to need an update before it will work properly in Ver 6. The Rhino 5 version still works well.
Behind the scenes, the plugin employs a technique similar to what Jeremy demonstrates above.
It refines the technique to maintain the fidelity and complexity of the incoming geometry.
This plugin was a port from a AutoCAD version that still sits on the shelves of the Exchange.
Granted, none of that may sound particullarly appealing - unvetted code and all. If possible, post some geometry. Let me demonstrate what the plugin can do, at least.