Although some people have described approaches from the south, there seem to be access issues with some of these routes, unless you're willing to cut directly across farmland.
Although an approach from the north is much longer (5km), it avoids these issues as it is mostly through Coillte forestry tracks. One approach is to park at R67055 76814 A, where a farmer has previously had no issue with walkers parking outside his farm building walls. Due to the length of this walk, it is too complex to describe here, so I suggest you follow the track indicated from this parking spot. It is a long walk, but nothing too strenuous and I'd allow 3 hours minimum for ascent & return.

(Also note, the parking spot indicate in sandman's comments below seems to be in error as it is halfway up a sloping field.) Linkback: https://mountainviews.ie/summit/774/comment/5533/