All I can remember from my visit 4 years ago, is that I parked off the road/track in the middle of nowhere, and clambered uphill through peat bogs and streams (I got wet, which is unusual for me!) and over a couple of barbed wire fences.
It *is* visible from the road for a brief period, but disappears from view as you approach it, so you're going blind for most of the climb.
Best of luck!!