Again, thank you. And it is in my P_11.3, I'd simply missed it...

D'uh...

For the benefit of any-one else who's got lost thus in Cycles' maze of twisty little passages too-much alike:

In Material room (Advanced), right-click into open area to right of PoserSurface. Follow New Node, Cycles, Texture, left-click ImageTexture
Change Projection from Box to Flat. Click on Image field to browse to relevant RGB+Alpha Texture. Connect Color to Diffuse Color. Also, optionally, to Translucence_Color. Connect Alpha to Transparency. Also, optionally, to Bump. Dial to taste, render...
Take migraine meds...

Yes, a 'Gelatinous Blob', using an outer box with 'RachealMarie_in-the-flesh-seamless-tiles_74649' set's 'Flesh1 semi-transparent', which has an Alpha channel...
https://www.renderosity.com/freestuff/items/74649/in-the-flesh-seamless-tiles

;-)