By the way my vehicle, which is a locomotive, is not Mesh (so it is made of prims) and set to Phantom, the vehicle script itself makes it Phantom the moment it start moving.
OK I got it to work (sort of). What I did not know was that the 'rediect' prim needs to be a Physical object for this to work.
However after the 'rediect', the vehicle becomes physical and goes crazy, turns sideways, goes off the track, then stops functioning..
I also get a script error: Can't enable physics for object with physics resource cost greater than 32. Not sure what to do about that.
I am thinking that the KCP Redirect script will not work for my purposes.