Spreadsheet calculation of Know Sure Thing

Where can I find out how to do the spread sheet calculation of KST with ROC periods:
6,12,18,24 and average is EMA 9

I know how to do EMA calculations on a spreadsheet. Here's a link to a spread sheet (of mine) that calculates EMA 3 and EMA 15:
https://dl.dropbox.com/u/1584180/EMA 3 15 Spreadsheet.xlsx

Does Sharekhan do KST (Know Sure Thing) correctly?

I'm trying to use a spreadsheet to emulate how Sharekhan's Trade Tiger calculates its KST at least until Sharekhan has 60 days of backfill.