Start at Kilmashogue Car Park, Wicklow Way, then DMW to Fairy Castle & Three Rock (could just stick to Wicklow Way here), drop down to Wicklow Way, up to Price William Seat, along the county boundary, over Cloghnagun and Glendoo (boggy here), down through Cruagh Wood, over Tibradden, and back to Kilmashogue.
Alternative: could start at Cruagh or in Glencullen Valley, and cut out the Kilmashogue leg.