Centrafuse is not a replacement software package that can run on a factory navigation system. There are other parts that will be needed in order to get Centrafuse to connect to the screen. You will need to get a video interface adapter that will allow you to connect the video output of your Centrafuse system to it and then connect the adapter in-line to the video of the factory navigation system. You will also not be able to use the touchscreen functions as they are tied to the navigation unit and can only control those functions. A good product to replace this function is called the Space Navigator.
Here is a video showing it in use: