By Nikos - Computer Science Student 

Instructions:
1. Go to the system files. For Mac users go to the game Open Package Contents. For Windows users go to Program Files, you will find what you need in there.
2. Just replace the files in the folder given.

-- HUGE WARNING --
If you have made any other changes to the files given (mostly the base.effects file or if you have a skin for the occultist). DO NOT REPLACE THE FILES. Open the files given and specifically copy the information that was changed.

Although if you know how to modify game files you probably already know this.