If you have a MATERIAL* and write something like effect = "myLittleShader.fxo" instead of = "myLittleShader.fx", the engine loads the *.fxo instead of compiling the .fx file. Though remark, that you have to use a shader that is designed for usage with Gamestudio. If you have an .fxo file from another game that wasn't created with Gamestudio, it is rather unlikely, that you can run the shader with Gamestudio (even though it's based on HLSL). And I doubt that you can recover the original HLSL shader code, unless you figure out how to decipher the compiled shader ASM instructions so that you get a sophisticated understanding for what is going on.