This can be picked off as part of a clockwise loop from the northern side taking in Stradbally, Beenoskee and Beenatoor also. See track 3158 for a detailed description. Coombane is the final summit visited so I've only included directions back to the road in this post.

The summit itself is relatively flat on top but there is a steep drop to the northern side so take care to locate the ridge (quite a well defined grassy track) running northeast and descend (keeping the steep drop on your left) until it is possible to drop off the ridge and into the valley below to the north. You will need to cross a small stream, before picking up the pathway Q5689 1041 A (initially grassy, then becoming more stony) which leads back to the road at Q5657 1171 B. Ideally, have a second car here to avoid a 4k trek back along the road to the start point. Linkback: https://mountainviews.ie/summit/254/comment/18399/