i already do this just not in depth and i do it in my own mind.
you have to take 1 bid per conference into account, then just start counting out spots and keep track of how many conferences are not represented and stop at 64
example, if u counted out 50 spots and then 14 conferences are not accounted for in the top 50, you stop cuz ur at 64 and that is ur cut off point
you can estimate seeds be dividing by 4, i never bothered with the poorer seeds, I have only really done this to see where teams in my conference fell.. usally took 2 minutes or less to figure out.