It's a long list of rules, and most of it involves cross indexing the Tarot with The Book of Unspeakable Fabrics, so I won't post it all here. But here is rule #473:
473: A= B D A, B= A A, C= D C B, D=B D. Start with the sequence B A C A D D, and apply the set of transformations n times, where n is the number of the day of the month divided by the number of the section of the night sky where Sirius can be found tonight, rounded up. Convert to the Tarot with A=The Fool B=The Lovers C=The Hermit D=The Hanged Man. Concatenate the outcome with the result you found in rule #118.