Is it possible to change to different shaders through scripting?

[Gunrock]

I have two different shaders planned for my upcoming horror themed mod: "Braham Manor: Remastered" . I have a Old Video shader and also a Pixelated Film Grain Shader. My question is it possible to script the effects at different times through out the map? The mod is going to be used for GZDoom.

 

Thanks!