It is possible to park around V 636 851 A. This is one place that you can park if you are intending to do the entire Glenbeigh Horseshoe, going right around to the north western edge at Drung Hill. From there you can walk back on roads and tracks to the parking place. If you had two cars or had other intentions, then there would obviously be other options such as starting from Creeveen (V670 849 B - but I haven't actually tried this)

According to Seán Ó Súillebháin [Walk Guide: Southwest of Ireland] it is possible to walk directly up Knocknaman, the spur behind Lake Coomnagrossaun in the picture. However for getting up Macklawn I would recommend heading for the col north of Macklawn, towards Beenreagh. Linkback: https://mountainviews.ie/summit/259/comment/1858/

The summit of Macklawn (Macklaun on the OS Map) is not particularly exciting. There's a smallish cairn on a rounded top. However it is a good viewing point. If you are visiting it as the start of the Glenbeigh Horseshoe, then you can see the finish on Drung Hill, though there's only hints of the walk beyond Meenteog. There's also a good view of Colly.

Central beyond the immediate green summit area in the picture is the ridge leading away. Left of centre on the skyline is Seefin (493m) with Lough Caragh to its right. Left of the picture on the skyline is the bumpy low (270m) group of hills that you will encounter if you go south west from Glenbeigh. Linkback: https://mountainviews.ie/summit/259/comment/1859/