the "total conversion"?

Out of curiosity is it possible to create a mod that will completely overwrite the standard core races (and DLC) without actually changing any of the original files?

To my knowledge there is no way to over ride the core files without replacing them.
I have tried several methods, each meeting with varying degreeā€™s of sucess.

In the end it depends on what your trying to do and which work around method suits.