This is a bugger to find even with a gps. Approached from the direction of the 4 poster it's impossible to see this cist until you fall into it as it is beneath the level of the heather, approached from the north however the large boulder becomes evident from a few metres away. This boulder looks like it may be earthfast while the other stones look pretty rough and ready, this is no elegant slab lines tomb but it does have a charm of it's own, Stu mentions 2 sides of the cist being visible but I could only see the stones of the eastern side, any others must have been buried under the heather.
You'll probably need a gps to find this cist unless you have a few hours to spare. There is a large rock nearby that sorta becomes visible when you're on top of it and so is something to look for in the thick heather....I think it is part of the boundary bank the cist is built into.
Two sides of the cist are clearly visible and constructed of fairly large stones.
If you have a gps then SK28157 71021 should get you to within a few metres of it.