Found a reference to this in Meyn Mamvro, so thought I'd check it out. It's best to approach this from Engollan, as the road from the main coast road B3276 is gated.
Access to the stone is straightforward: park by the farmhouse, cross the road and walk along the footpath to within 50 yards of the stone. I had to duck under an electrified fence, and the field had plenty of evidence of ruminant activity.
The stone, which stands around 5 feet, looks a bit precarious, as the packing stones are exposed and there is an evident lean, but the stone itself has a wonderful shape and colouring.
There is a nice view of the Atlantic along the valley to the nearby coast, but otherwise, not much in the way of obvious sight alignments.