For those who may be experimenting with developing a ghost material, I think that transparency is not going be satisfactory.  Bagginsbill's ghost material from some years back uses refraction;  that is what I'm using.  It will only "see" the forward-facing polys.   This allows you to move the camera or re-pose the doll and still get the desired effect, whereas a transmap would only work for a fixed perspective.

I also added in lightcasting (look at the ground beneath the fire sprite, and the metal tabletop under the green wireframe sci-fi girl).  If you use @SamTherapy's method, you could render the background with a blue point light to compensate.

Render settings will need to allow for plenty of transmission bounces so that the refraction can reach back to the camera.  If the doll's mouth is closed, apply the invisible MT5 to the inner mouth parts;  that will reduce the number of transmission bounces needed.  I set transmission bounces high, like 64, since the render engine will only use as many bounces as needed to complete the raytracing path anyway.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5