KIA vs. Sicilian?

Fischer used to play it as white but only against the 2.... e6 sicilians I believe.

Usually against 2.e6 setups.  Against other Sicilians it isn't as strong, but almost anything is playable below master level, if it saves you some study time and you like it, go for it. 

Just realize you aren't going to get a quick attack with it.

You could try the closed sicilian, it seems to have some similarities to the KIA.

If you use a KIA and the sicilian ends up with a c5, d6, e5 pawn structure it provides white with some difficulty. Well, at least it did in my case when I had to face it.

The King's Indian attack - Move by Move by GM Neil McDonald (2014)

Starting Out: King's Indian Attack by John Emms (2005)

https://web.archive.org/web/20140627034051/http://www.chesscafe.com/text/hansen81.pdf

Starting Out: Closed Sicilian by Richard Palliser (2006)

https://web.archive.org/web/20140626175558/http://www.chesscafe.com/text/hansen87.pdf

The K.I.A. can be used against the Sicilian effectively; however, the Sicilian is unsolvable. There are new variations invented seemingly daily. It's somewhat ironic that even though white has some advantage in all Sicilian systems, it's the most problematic and the best course of action for black. The K.I.A. is very flexable but not winning, not by a longshot; white just has so much flexability that it's always worth it. It's a matter of taste: If you like immediate pressure and force, either play the open Sicilian or the Grand Prix Attack (Highly recommended). If you like manuvering, positional chess, and using the imagination for something different and special, use the K.I.A.