Shaders Per Game

As you may notice we can save per game configs in the config folder, however i cant seem to get shaders to work, iv a overscan shader that id like to use for spyro 2 and 3 so it gets rid of the black bars, i can get it to work doing the usual way of loading the shader

But is there not a way to add it to the configs
Its got 2 lines called
GPUShaderDir=shaders\
ShaderDir=

But i cant find how to load my Overscan shader