It shows how to combine the rotation matrices with a translation to achieve the rotation about a given point. The page you found gives you the rotation matrices for each axis rotation R

_{0}. The article I pointed to gives you the two transform matrices T

^{-1}and T.

The resulting matrix for the rotation about the point (x,y,z) is then:

**R**

_{(x,y,z)}= T^{-1}* R_{0}* T**Alternative notation:**

**R**

_{(x,y,z)}= T^{-1}x R_{0}x TBest Regards,