I found this quote in an article called "Gaelic Historical Songs" in "The Scottish Review," 1891.

The massacre of Glencoe is the subject of an
elegy§ of unusual merit by the bard of the murdered chief.*

§ 'Mile marbhphaisg ort, a shaoghail,' MacDonald, p. 241. The version in Sinclair's Gaelic Bards, p. 138, begins 'Lamh Dhe leinn, etc.'

* Hence called Bard Mhic-'ic-Iain (the family title of the Glencoe MacDonalds being Mac-'ic-Iain). After the massacre he lived in the island of [Muck?], and is hence also called 'am bard Mucanach.'

Here's another quote from Papers By Gaelic Society of Glasgow, 1908:

This "fairplay of the Fiann" has become proverbial in the phrase "cothrom na Féinne," which is used in the poem on the "Massacre of Glencoe" by the Bard Mucanach:— "Had there been the fairplay of the Fiann between yourselves and the Lowlanders, the shaggy birds of the hill would be croaking foully over the bodies of the others."

Na'm b'e cothrom na Féinne
A bhiodh eadar sibh féin 's clanna Gall;
Bhiodh eòin mholaich an t-sléibhe
'Gairsinn salach air chreubhagan chàich.

That's the only quote from the actual poem that I've been able to find. Of course someone who could actually read Scots Gaelic might do better than I!