I did it once on my first try but failed on my second (last night). When it worked my first time I was incredibly tired and very very close to falling asleep. The FILD technique popped into my head at the last moment and I moved my fingers a couple times without thinking about it much at all..I pretty much just focused on the movement.

The technique I think is just another way of keeping you conscious while your body falls asleep. It's easier for me to use because when I try to keep myself awake in my head (i.e. 1 I'm dreaming..2 I'm dreaming..etc) my thoughts tend to trail and I just fall asleep. If I'm doing a small movement that's physical I can focus my attention on that while I fall asleep.

Hope that helps lol