This has the makings of a classic horseshoe walk. Hard country and hard to get at, but I hope the following will make the latter aspect somewhat easier.
On a fine Sunday 3 June 2018, we took in Com na hEorna as part of a loop walk also encompassing the Sliabh na Seasca and Sliabh na Seasca South Top.
This route allows reasonably easy (?!) access and return via the Kerry Way
We parked at a layby at V67299 69156 H, returning south along the road to meet the Kerry Way at V67380 68612 I, turning north west along the small side road. This passes some farmhouses and presently degenerates into a gravel forest road. Keep following the Kerry Way until hairpin bend at V65956 68647 J - leave the Kerry Way at this point - go straight, don't follow the bend. Follow the forest road WNW and then N. You will see the northern ridge of Coomahorna in front of you. Leave the forest road, travelling NW a 100m or so across the cutaway woodland, and go up the slope to gain the ridge at approximately at V65227 69193 K. Follow the ridge (travelling in a SW direction) until the summit is gained. It looks dodgy from below, but presents no particular difficulty as long as you stay back from the cliffs on the northern edge of the ridge.
The views are absolutely outstanding.
From here, we descended carefully to the north west and across the ridge to take in the Slieveshaskas. Rough country and potentially dangerous in poor visibility. Although the going was slow, we encountered no particular difficulties.
We descended along the eastward ridge between the Slieveshaskas to somewhere around V65644 70152 L. We carefully descended a ramp SW until we reached the valley below. We then made our way down down the valley to regain the forest road we started from near V65785 69199 M. Follow the forest road back to the Kerry Way and back to the starting point.
This little jaunt took a very fit and experienced group of (four) walkers seven hours under absolutely ideal conditions. I'd allow enough time and I'd be wary of doing it in poor visibility.
That said, it's a personal classic and superior to most of the more high profile walks around the country. Linkback: https://mountainviews.ie/summit/294/comment/19943/