You make your way along the path until you hit the babbling brook (make sure you choose the right paths) - this should take less than an hour from both the east or west trailheads.
Once on the bridge over the brook....let your GPS lead the way.
One more thing: You might get wet feet, depending on your willingness to climb ;)
Happy Hunting!
P.S.: GPS coverage is poor - make sure you get a fix by getting it into an elevated and clear position. After you're done, put the cache back securely, otherwise Hong Kong's strong rainfalls will wash it away!
Small note on cache maintenance: I'm here frequently, but also have back-up local help if needed.