It's not entirely true that Poser lights can't project an image in SuperFly. Don't get too excited though... It handles coordinates in light shaders very differently than Firefly does.

Firefly light shaders map UV coordinates over the light's area, regardless of the light's type. That made applying textures and shaders to lights fairly intuitive. What you get in the preview is basically what you'd get from the light.

As far as I can tell, lights in SuperFly can only use world-space normal vectors.

That can be used to drive an EnvironmentTexture node and project an image. The downside is that light normals are stuck in world space, which means the texture map is stuck in place regardless of which why the light is pointed. Point a spot light up, it protects the top of the image; point it down and it projects the bottom. The middle of the image will stay in the exact same point on the wall.

The same setup can be used with a point light, only the light orientation has no effect at all. The image can be manually aimed with a vector Mapping node, though that's hardly convenient. And the orientation displayed in the texture node preview isn't what you'll get either. The actual output is flipped and rotated backwards. As for the other types of lights, they only give single normal value and are useless for image projection.

[My apologies for the weird display. I got a new monitor and Poser's UI scaling doesn't seem to work correctly...at all.]

While light shaders and textures in SuperFly are less practical than they were in Firefly, I just wanted to set the record straight in case someone might find the info useful in some way.

One case where I do find Superfly's quirky lights useful is protecting a light or shadow from a specific part of the environment map. Flip the Mapping vertically by setting the second Scale value to -1, then position and aim the light where the light/shadow in the image would be cast from. In my experience, this gives a more defined light/shadow projection than using an environment sphere by itself.

The sun is partially obscured by trees In the environment texture. However, the lighting is too defuse to get a defined shadow. To emphasize the shadows cast by the trees from above, I used the environment texture in the shader above with a spot light. I'd previously done the same effect in Firefly by fiddling with the image scale and offsets to get the shadow of the tree limbs, but I actually found doing it in SuperFly to be easier.

Not exactly easy, just easier.