Corey Barker has an interesting Photoshop Extended example of 3D text as a volumetric solid ala Superman titles at Planet Photoshop. In a square file, he duplicates a text layer and turns them into a 3D volume using 3D > New Volume from Layers. The chunk of light imports into After Effects fine but you have to make the layer 3D (not just the Controller) for it to accept Lights. You also might animate the Camera and the Z-scale of the Controller layer.
Chad Perkins showed various CS4 methods of Converting from 2D to 3D and did something similar with DICOM images.
PS 3D in AE can be a bit wonky, and options include mass Z-space manipulations or the use of Trapcode 3D Stroke (see lightcycle.mov), or the 2D Echo filter built into AE as sketched by Chad Castleberry in his After Effects tutorial on YouTube (or more drawn out in a Vimeo revision):