The starting place "GlMacnass" is at the car park at Glenmacnass. Be aware that this carpark is notorious for breakins. Also, when setting out inspect the level of the river. If it is uncrossable or becoming so, take account of this.
Despite the title, the walk as actually done didn't reach either Tonelagee or Mullaghcleevaun though it could easily be extended to reach both.
The way up via the north side of Lough Ouler is relatively easy with a continuous but not over demanding gradient. Underfoot this is likely to be somewhat boggy after a lot of rain but as of early Sept it was ok
Barnacullian, the ridge between Stoney Top and Mullaghcleevaun, is composed of exposed decaying bog. This route avoids some of the worst of it.
The route through the trees to the south of Carrigshouk is useful because it connects to the side of the Glenmacnass River. It is possible to walk on either side of this river. Be aware that after heavy rain the river can flood and become uncrossable. This would be particularly relevant were you to do the walk in reverse.