Slieveboy stands in splendid isolation, offering 360 degree panoramas to the Blackstairs, south Wicklow Mountains, and the Irish Sea. We approached from the south and east, parking at the forest track entrance at T02728 57076 B, and following the forest track shown on Sheet 69 to the south. This eventually gets you to the track shown running N-S on the ridge south of Slieveboy's summit, though Sheet 69 isn't 100% accurate here. The tracks wind their way east and north up to the summit, which gives new views around every corner.
The summit itself is a complex of no less than four telecommunications installations, complete with masts, transmitters, and associated equipment. I guess the attributes that are good for all-round views are also good for telecoms companies. In spite of all this development, the summit itself is at least accessible. Linkback: https://mountainviews.ie/summit/739/comment/3160/