What I'm basically looking for is a spreadsheet that shows the estimated odds decay based on given starting odds, along with the odds if a goal is scored - which Soccer Mystic does exceptionally well, but I'm exploring whether I can put that information into a spreadsheet, so I can apply automation.
Good luck making money using simple poisson distributions to predict the odds, Jeff, you'll be up against teams using much more sophisticated methods of accurately predicting the probabilities who also take into account the state of the games ,team selections etc.
A simple google search should find you plenty of spreadsheets and the usual idea to get goal decay over time is to multiply the starting goal expectation by the proportion of minutes remaining to the power of 0.84 i.e. 85th minute would be = opening goal expection * (90-85/90)^0.84 generally based on the statistics that 56% of goals are scored in the second half.
For the current score poisson would simply use that as a starting point as it's only predicting the likliehood of a goal. So say the score was 1-0 you'd use that as the starting value and a poisson prediction of 0-1 would simply become a score of 1-1 with it's associated probabilty and once again you add all the winning, losing & drawing outcomes to get your overall win lose draw odds.