Parking is available at N50 18.474 W 004 45.845, or rather nearer the cache, but along a potholed lane at N50 18.357 W 004 45.683. The most direct path to the monument starts at N 50 18.289 W004 45.681 and may be very muddy. An alternative route is via the Cornish Coastal Footpath.
If the coordintes are correct and your GPS is working you should be standing near a large granite slab.
Stand with your back to it and follow the clue