unclued
The code is quite simple.
I don't use M$ products if avoidable, so have no idea about Excel. Openoffice Calc proved too tedious because of the letter transformations - it will do base conversion, but changing to ZAB...W was messy.
Some progress solving by inspection, but, at the moment, I can't see how anyone could do it just with a calculator (or spreadsheet).
Solver's blog should be interesting.