First, here is a quote from the readme of the Assault Game Mod for YR :

If you are using XCC Mod Launcher to enable your mod, then your PKT file should be added to the Mod Launcher's VIDEO section (no, the PKT is not a video, it's just that by putting it there will cause the Mod Launcher to write the PKT file to the \RA\ directory without attempting to process it in any way).

So my question is : can you just make an "Input" section where we put the required files for our mod ?
I mean, if needed we can create our own MIX files and put stuffs inside...