Shane is spot on with the location of the graveyard. The monument is the best way to locate the graveyard which although only 20-30 feet up the lane can't be noticed from the road, so do look at his link so you know what you are looking for. The sign from the r744 at Castleellis crossroads is for Blackwater, its about half a mile down that road opposite a whitewashed farmhouse. The graveyard is always accessible by foot and is well kept but many of the stones are hard to read, its smaller than Oulart Old Graveyard and it won't take too long to look at all the Gravestones. If you go in the other direction from the R744 it will bring you to Ballaghkeen village, via Slievenagrane townland, there is a very small old graveyard in the village opposite the Church it also is a possible burrial place for people living in Slievenagrane in the 1800's.
Good luck
M