The topic of wild tiger trout has been discussed a good deal here on our forums (try Advanced Search at the bottom of the page to hit these threads).
As for catching them, I've managed quite a few stocked fish from various sources, but in nearly forty years of fishing in PA I have never caught - never even seen - a wild tiger tout. They're very rare. There does seem to be some consensus that they are, relatively speaking, somewhat more prevalent in north central PA and that certain streams seem to produce 'em. Needless to say, tiger fans are tight lipped about these creeks.
Whether you can craft a game plan to catch a wild one is debatable. It would be a fun quest, but speaking personally, I wouldn't make success too important. Go in expecting to fail and just enjoy the fishing. Focus on mid sized freestoners with mixed brook/brown populations. With that said, some folks here on PAFF have caught wild tigers early in the FF careers and some particular fish have been caught multiple times by different forum members.