3d Helmert Transformation


I am using MS v8i ss2.

I would like to develop an excel calculator to apply a Helmert 3D Transformation to convert from site to state plane, northing-easting coordinates.  I have a decent book (by JC Iliffe) and many white papers on the subject, but keep encountering math issues with my calculator.  I am unsure about calculating the unknown parameters and would like a detailed example I can learn from.  I was hoping a technical person in the forum could offer any suggestions of a Bentley site, other book references, blogs, etc. that may have more detailed calculations / examples.