Some years ago, I came down a very rough track from Sharp Peak, down to ridge and then along to the saddle between Chek Keng and Tai Long (dark by the time we were part way down; once at bottom of main slope, used keyring flashlight to find a sign warned of dangerous slope, which people shouldn’t go up!).
I think this is still viable, though difficult, and warned against (not sure if there are any official trails to the top).
The one you mentioned is the right direction.Just pass the the water installation and you will reach another saddle (Nam She Au). You can see the eroded path on the right leading to the summit. It is the common trail that the hikers follow (up and down), though it is quite eroded and slippery.