There is precious little point in complicating Donalds Carn. Turn off the B90 north up Island Magee at (467971 A) up the Gransha Braes road. In about 800m (475972 B) you will meet a crossroads; go straight over it, and at the T-Junction at (479974 C) turn right.

Find somewhere to park close to the aerials conspicuous on the right hand side of the road after 300m or so, and then exercise your judgement by deciding which of various candidates on either side of the tarmac is the highest point. There's a chance it might be a patch of grass in the aerial's enclosure (which would be unfortunate, given that there's no obvious way in if the gate is shut), but it seems more likely to be one of the low embankments either side of two ditches running east from the road.

If you climb over the fence in this direction and wander down the field you'll eventually get a nice coastal view, but there's little else of interest hereabouts. Linkback: https://mountainviews.ie/summit/1357/comment/15601/