Modifying the illumination Shader

[The chaser]

Problem is, the shaders seem to be applied to things with in-engine code, correct me if I'm wrong but there's no way to 'apply' any of the available shaders manually, so adding shaders won't work.

Problem with changing the code of the existing ones, assuming you could get around the errors from not having control over the process, is that all of those articles suggest you need to apply several shaders to get that effect.

There is a bloom shader in the core\shaders folder, including the vertex & blur frag shaders & the other one to tie them together (i really have little idea how this works btw), so it seems like it's all there, but back to problem 1 ... how to apply it?

Maybe you could make an IFC with all the "core" shaders in a folder, just like an Amnesia inside an Amnesia. The changed shaders would be there, and would be used just for the IFC.