Park at Larrigan near Lough Talt, or at the other end at Dromahair.
(Content below from Irishtrails.ie, where you can get more detailed route information)
The Sligo Way is a 74 km route that traverses the County of Sligo in the northwest of Ireland from Lough Talt, in the Ox Mountains near the Mayo border, to the town of Dromahair in County Leitrim (or the other way round).
There are magnificent views east over to Ben Bulben, north across Donegal Bay to Slieve League and west to the Nephin mountain range from the high moorland in the Ox Mountains during the early part of the route, and some pleasant woodland lakeside sections towards the end.
As the route begins in the mountains, the total aggregate ascent over the entire route is only 900 metres, and there are no significant climbs involved at any stage. Attractions along the way include a crannoge or early lake dwelling on Lough Talt, megalithic tombs, which are abundant in west Sligo, and WB Yeats’s Lake Isle of Inishfree on Lough Gill. But for short boggy and wet sections near Easky Lough, Ballygawley Woods, Lough Lumman and the Lough Gill area, the route provides, in the main, an enjoyable and comfortable walking experience.
Terrain consists mainly of forest tracks and ride lines, quiet side roads, and open moorland paths (often wet and boggy in places). There are no accommodation options available for about the first 40 km of the route, but plenty thereafter.
If you get the OSI maps 24 and 25, you will be able to see the whole thing in context, and it makes planning your route a bit simpler.