Sure, Lam, but they're not really "secrets" so much as aspects of a basic strategy that anyone who fishes extremely pressured water learns eventually:
First, recognize that pressure is the main issue to overcome, and that the very competitive situation--many trout crowded together--is your primary advantage in a stream like the Little Run (or the special reg. section of the Little Lehigh, etc.). The fish may be extremely suspicious due to the angling pressure, but they still have to eat.
Overcoming the influence of pressure is about not falling for the trap of just pounding the water with standard approaches and presentations. People do this on places like the Little Run or the Little Lehigh because sooner or later they manage to catch a fish that way, and then they think that it's just a matter of flogging away until another one makes a mistake. You end up with a sore arm, few fish, and no reason to ever expect more than that.
Because the stocked fish in these places don't flee at your approach, it's easy to think that it doesn't matter. But watch the reaction of the freely feeding fish when an angler appears--they don't flee, but they do know the angler is there, and they react with increased suspicion (even with regard to natural food). This is why the first cast or two to fish that haven't been alerted to your presence often succeeds in this situation, sometimes no matter what fly is presented. Often, a change of fly or presentation can also get a quick response, but after that the point of diminishing returns is quickly reached. However, sometimes you can play that tactic over and over again by finding a few "relaxed" fish; approaching them as though they were spooky wild fish; catching a couple; and then moving on to the next situation. On the busiest days, this approach has obvious limits.
When a hatch is on, the fish will often keep feeding even when being pounded, so "hatch-matching" flies or presentations that have a degree of novelty can succeed over a much longer period of time in one location. (The fish are getting confidence from every real bug they eat, and that helps.) Just remember that even the best flies and presentations can go stale if they are constantly shown to the fish. Sometimes "un-matching" the hatch can get a reaction from fish that start refusing your best imitations, but that usually is only good for a fish or two. Unique presentations can be every bit as effective as unique flies. I can't tell you how many times I've caught fish that had grown indifferent to the constant drift of my flies just by letting a fly settle on the bottom in the shallow water along the edge and waiting for a nearby fish to amble over and pick it up. What's known as "thinking outside the box" is often rewarded on pressured streams.
Another thing to keep in mind is the rule that fishing pressure is never evenly distributed, even on tiny, seemingly shoulder-to-shoulder places like the Little Run. If you look carefully, you'll notice that there are a few small spots that are hardly ever fished. These places are either tight because of overhanging brush or just more difficult places in which to cast or drift a fly. Play the laziness of others to your advantage, and you'll find that the fish that hide in these more difficult places are much easier to catch than the ones that sit out in the open under the constant flogging.
Finally, keep in mind that the social pressure among the fish is unusually high in these "artificial" situations--almost like a hatchery trough at times--and the competitive reactions of hatchery fish can often be their downfall. Sometimes, where the population is especially dense, a particularly appealing presentation (say, the sudden plop a fat beetle pattern or even an egg pattern hitting the water) will draw an instant reaction from a mob of fish that may all turn away at the last instant. When you see this competitive reaction, use it to your advantage. Even extremely "educated" stockers can be put off their caution by seeing a neighbor pursue a meal. Fish are naturally stimulated by the feeding activity of other fish, and when that activity gets competitive, they can be persuaded to make rash decisions. One way to exploit this is to rest the water for a moment or two when you see the gang reaction to a fly. Then present and withdraw the same fly several times in rapid succession. The frustrated fish will mill around excitedly, and when the fly finally appears without being withdrawn, one of them will usually be stimulated to do something dumb.
So, as for the true "secrets," Lam, I'll keep them to myself, thank you. But I hope this overall strategy and some of the tactics I've used as examples give you some ideas and lead to more success in these situations. Have fun, but don't get greedy. Remember that even the best hand can be overplayed. ;)
Best,
Gonzo