Here are the notes described: https://pdfs.semanticscholar.org/771c/15fba0308428ae1a2bf8db9c8f8d1b63eb3d.pdf
My Attempt:
This is what I tried, but then I realized that this would not end with 9-points. I tried to use the centered difference approximation for the points immediately around the center and then again for the points next to those.
