its possible to do through the transparentcy sliders but I would do it in post myself. You can buld your scene and render the image , save it as a PZ3 . Then hide or remove every thing but the character you want to look jelloey. Render that and save it as a PNG or TIFF or PSP. This saves it with a masked layer so its only the character. I useally do it in 3 parts . I have the complete scene charater and all, just the back drop and just the charater. Then just bring then all togeather in the same image in layers.