Can't see a way to alter the GL configuration from lua

I’m using just one directional light and no point or spot lights in my 3D game, so it makes the shaders
inefficient to have maxPointLightInShader and maxSpotLightInShader set to one. From C++ I could access the Configuration class and call setValue to update these settings, but I’m using Lua. Is there a way to do this from Lua? I wondered if perhaps there was a standard location from where a config file might be loaded if present, but from reading the code I can see no sign of it.