Yes, most of the math involved is in the first post, but the initial seed finding is not actually documented very well. If you really want to do it by hand I can go into the details with you via PM, but be warned that it's likely going to take you some days to actually do it by hand. In particular, going from IVs to seed will require you to do 65535 calculations and then there are a few thousand more after that to plow through the probable seed candidates.
Is there a particular reason that you don't want to use the program?
Is there a particular reason that you don't want to use the program?