It depends on time settings heavily. Might be a bit more possible on long-time settings.
I guess the best way to be able to find this is to drill yourself to death on tactics :P
I'm definitely not good enough to spot that, but someone who has spent several hundreds or thousands of hours training tactics puzzles would be able to see it, given enough time.
So in one of my recent games I had a very good position, but wasn't really sure what to do. I missed my chance and even though I eventualy managed to win, the game was more difficult than it should have been. When I later confronted with computer, it showed me the best line, but it was beyond my abilities. So what would your ideas be in this position, how would you find this line?
The advantage at the end isn't hard to see, but how would you find this line? And how many moves ahead can you calculate with confidence?