Many routes are available for this summit, the only Vandeleur-Lynam on the Inishowen peninsula.
One place to start is from the unfenced road at around C4426 3722 A. While not an inspiring route due to the wet untracked and vegetated terrain, this has the merit of making it easily possible to also go to Damph.

Another eastern route uses the bog road starting at C450393 B.
From the west at the Slieve Sneacht Centre in Dumfries where there is parking at C3854 3895 C
Or from near a derelict cottage at C392 368 D.
From the north it is possible to start at C42498 41978 E or C408423 F

The summit has a collection of amateur cairns built from the plentiful supply of loose rock near the top. Near the trig pillar is a well which supposedly has a cure for eye problems (or maybe a cause?). There are fine views to the Loughs Swilly and Foyle, to the sea, to much of Inishowen, to Muckish and to the Sperrins. Linkback: https://mountainviews.ie/summit/250/comment/5010/

I reached the foot of the mountain by the road marked 'dead end' C38868 40108 G. After driving about 600m I reached the gate. So far, I have walked through gates marked 'close gate' many times, but this time I drove through by a car. And, after closing the gate C39521 40119 H behind me, when I found myself at the crossroads of dirt roads, right at the bottom of the mountains in front of me, it was like in another world that I reached with my vehicle, leaving the whole civilization behind me.
It was just before 8 p.m. A quick glance at the calendar revealed that sunset was supposed to be at 8:50 p.m. I can't do this, I thought. I walked briskly towards the top. A few hundred meters along a dirt road, then avoiding clumps of grass and peat holes. It wasn't that bad, it hadn't rained for a long time so there was no mud, but I fell into the swamps two or three times. Time, however, passed inexorably and the sun was getting closer and closer to the horizon. The climb to Slieve Snaght is quite steep from this side. I have the sun setting behind my back so I didn't really see what was going on there. The last meters to the top, long strides on the stones and I found myself on the top where there were lots of small piles of stones. I quickly located the main peak and when I looked back the sun was just above the horizon.
I took one picture... and the sun went down. Just one take, not even a chance for a repeat. Linkback: https://mountainviews.ie/summit/250/comment/23938/

'Walk Guide West of Ireland' (P.Simms & T. Whilde) gives a route from the east at 443369 I but I took the advice of Paddy Dillon in 'The Mountains of Ireland' where he describes this as "the shortest, boggiest and least inspiring route". I started from a bog track on the west at 408423 F, can park here where track forks. Walk up track , turn left and ford stream, turn right and at small quarry head onto hillside in front , aiming for some large boulders. There are a series of rises separated by flat areas of bog. The ground becomes rockier as approach the minor summit of Slieve Snaghtbeg (505 m) which is topped by a cairn. Cross over gap to the south for the climb to the summit. The summit is a weird scape of rocks and boulders, with cairns and very large walled trig point - it does feel other worldly (see pic for a little flavour). There are good views west across to Ragtin More and Urris Hills behind the shapely Bulbin and south to neighbouring Slieve Main. On a good day I am sure the views would be much more extensive. One and a half hours to the top and it is only logical to take in Slieve Main as well.No one else on the hill when I climbed on 23rd April 2004 Linkback: https://mountainviews.ie/summit/250/comment/1069/

This is the summit trig pillar on Slieve Snaght (Inishowen), with the peculiarity of being almost fully entombed in a cairn-like structure. Nearby I found the equally unusual feature of a pile of tractor and car tyres whose purpose was as unclear as it was unsightly. The jagged spikes of rock that cover the top (set up by pilgrims or just a whim of Mother Nature?) would make a dream-bed for a fakir. I started up from the E side, from a point on the bog road at C 450 393 B, walking over marshy land at first before climbing steeply up to the summit. There are long sheep fences on this side of the mountain, with ne'er a stile in sight, but enterprising sheep don't seem to have found that a great obstacle to free passage. From the top, I walked south to Slieve Main and then triangulated back to my point of departure. Damph would have been a further obvious top to visit, but on the hot and rainy day I did this walk the combination of bog and fence and Donegal midges got the better of me in the end. Linkback: https://mountainviews.ie/summit/250/comment/2759/

(Climbed 06.02.24) Having topped Crocknamaddy & Slieve Main (first part of walk) I reached the col beneath Slieve Snaght (C421379 K). From here it should have been a straightforward ascent, similar in nature to that I had just negotiated to make the top of Slieve Main. However, the climb was now a little further east than before and I wasn’t afforded the protection I had enjoyed while climbing Main. It made for a pretty miserable ascent. The rain, wind, and most notably the gusts which felt much stronger than the predicted 15-20 mph, appeared intent on hurling me of the mountain. Cold and feeling suitably miserable I approached the summit entreating Zeus (Weather God) to at least have the good grace to afford me a clear spell on the summit to take some pictures. He must have been listening because just as I cleared the top, the clouds, as if by magic were swept away, revealing the rock strewn summit, with its numerous mini-cairns and the large rock structure surrounding the Trig point. Unfortunately, while Zeus may have been magnanimous, my camera batteries and the spares decided to chuck a collective wobbly. After some minutes of violent shaking I managed to get one set to take half a dozen pics before they packed it in completely. Being cold and miserable I decided not to dawdle any longer at the Trig point and set a bearing of 246 degrees SW for the 4.5K trek back to Fallask. This route took me west of Slieve Main crossing the Sruthancarragh (C415385 L) after about 1K from the summit. Maintaining the same bearing crossing slightly marshy ground at times, I reached the Kinnego Rd via a track in a newly planted forested area. From here it was a five minute walk back to the car and time for a hot drink, quick lunch and twenty minute drive (via Clonmany) to Urrismenagh, the start of the final leg to the summit of Raghtin More (See Raghtin More for final part of walk). Linkback: https://mountainviews.ie/summit/250/comment/2199/