Do you mean a light that modifies scene normal of its affected surfaces?
What I understand is that something like a rain shader blends an animated rain normal on top of the scene normal. Is that correct?
BTW, the first one is quite simple. It is a projected texture that blends on top of the g-buffer based on the scene depth. But it should be done between the g-buffer generation, and lighting step. So without having access to these steps of the Framework, the only way to do this is to rewrite the whole Framework.
One other way that we currently use is to generate a decal mesh in an offline build step, and render it with overlay, depth mask and alpha blend settings. The results are good enough for us, as our decals can have normal and specular maps. But as it makes build step longer maybe I'll write my own Framework someday.