I see in Chris Bowick's book on RF circuit design, he provides 8 quite
long-winded formulas for converting between S and Y parameters and
vice-versa. I'm always prone to making careless errors (particularly
with signs) with these kind of equations, so I was wondering if
there's a simpler, graphical method for conversion using the Smith
Chart. After all, that's what it was devised for - the elimination of
computational errors in such calculations.
I've tried using the vastly simpler rectangular/polar co-ordinate
conversion formulas, but they don't plot correctly on the Smith Chart,
it seems.
So, does anyone know of a simple graphical way to do it on the SC?

It is possible to design a nomograph for anything- but I'm not going to
waste any time on your behalf because you're a low-life moron...-)