Surely the easiest way is to render the figure and the background separately, them comp 'em together in Photoshop.  Set up something for the figure to give a ghostly inner glow - Edge Blend does the job in Firefly - then render the figure.  Render the background alone, drop the figure in after and adjust transparency as desired.

Doing it that way, you have a transparent figure that is transparent only to the background, and not to various parts of itself.

Coppula eam se non posit acceptera jocularum.

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