I just checked a bunch of chainring bolts I have in my collection liberated from various Shimano, Sun Tour, Suguino and SR cranks. They all seem to be M8 in diameter but have neither of the two common M8 thread pitches of 1.0 or 1.25 mm so I'm not sure what the threading is.

The Shimano triple cranks I'm familiar with don't require spacers for the granny ring as the mounting bosses are long enough to position the ring properly. The SR and Suguino cranks do need them.

Bike tools Etc has chainring bolt sets and spacers avaialble. Look here:

http://www.biketoolsetc.com/index.cg...s&sc=Chainring

BTW, have you contacted FSA? They will certainly have the required parts available.