Visited this site in June of 2004 ... the tomb was a bit hard to find, even with OS sheet 84. Tall ferns everywhere! I suggest starting with the circle, rather than the boulder burials (which are easy to see from the road north out of Lauragh). We started from the burials and ended up combing the hillside for an hour or so. We did find several other unmapped stone formations, however, that did not appear natural.
From the circle, look south and head up the hillside. You'll catch sight of the fence surrounding the tomb. The fence around the tomb may be electrified, but there are gullies here and there that make it easy to slip under.
An alternate route ... further north on the road, past the boulder burials, you'll come to a fence that climbs the hillside. Walk along this fence through a couple of gates and look for the tomb on your left.