This is the text of the charm in Irish
This is my transcription from the above*:
"An t-Aithar Conn O'Domhnaill
ag díbirt a Lennan Síghe .i. an Stalcaire, ó Shíghile Tabaois.
Cros Chríosd ort a Shíghile, ód' ghearrán nuadh,
Cros fhírinneach Iosa ad choimead buan;
Ur an síghbharra ro shínear led' gheal-chnámha suas,
Ud choimhdeacht 'san oidhche 's ad chufáil chruaidh!
Ní bhfuil sígh-bharra ó'n n-dílinn go geal-tráigh thuaidh
Maoil-chnoic ná mín-lir le cruinneamhuil sluagh;
Ná h-aoirfead le laoithibh na sean-rádh suagh,
Muna g-cuirid ó Shíghile an spreasán duairc!
Sgríbhfead go h-Aoibhill go geal-tráigh thuaidh,
Ríg-bhean na bruighne 's lionán sluaigh;
Díoghaltur ir díbh-fheirg, ir cufáil chruaidh,
Do thabhairt do'n t-sígh-barra so Shíghile 'sa chongmháil uainn?
Saoilim gun sígh-bharra gan choimead cuan,
Do díbridh ó shíghe-chnoic an Lorán Ruadh;
No fíor-spreas o Aoife na sean-radh i d-Taudhmhumhain
Do sgaoileadh le draoigheacht-chlir na n-Danann n-duairc!
Sgaoiliom le síghe-chnoic an spreasán uainn,
No le slim-shreabhaidh líossa na srután luaith;
D'á chuibhrioch go cíocrach le Seannaid shluaigh,
Tre luighe leatra, a Shíghile, gan chead d'fhághail uainn?"
And this is the English translation from the book;
"Father Conn O'Donnell
composed this song in order to expel a Leannan Sighe, or incubus, from Sheela Tavish.
The Cross of Christ be upon you, Sheela, against your new incubus,
Let the true Cross of Jesus protect you forever;
From this fairy that lies close to your snow-white bosom,
Who accompanies you at night and gives you hard cuffs.
There is not a fairy that existed since the deluge, even those of the white northern strand,
And of the broad-topped smooth lioses where their hosts assemble,
That I will not satirize by the lays of the old sayings of the sages,
If they will not banish this dull midge from Sheela.
I will write to Aoibheall of the fair northern strand,
The Queen of the Bruighin, and the Familiar (spirit) of hosts;
To inflict vengeance with the wrath of hard cuffs,
Upon this fairy that haunts Sheela, send him away from us.
I suspect he is a fairy that has no place of rest,
And was expelled from the fairy hill of Loran Ruadh;
Or is a genuine imp sent from Aoife of the north,
That was loosed by the expert spells of the surly Tuatha De Dananns.
Let us expel to the fairy hills this sullen midge from us,
Or to the bright waters o the Lee of the rapid currents;
There to be strongly fettered by the Shenad [Shannon's] hosts,
Because he slept with you, Sheela, without your leave."
I'll point out quickly to start that the English translation is a bit loose from the Irish. For example the two terms given as 'incubus' don't actually mean that. We have stalcaire which can mean a stubborn person or a stalker, and gearrán which is a term for a horse, often a gelding. We see a similar thing with the word being glossed as 'fairy' - sighbarra - which might more accurately read as 'barrow fairy'. That one is worth noting as it specifically identifies this leannan si with the barrows, or ancient burial mounds. In the same way when the text calls him 'a pest' or an 'imp' sent by Aoife the Irish term spreas means a 'worthless person'.
This is a really fascinating piece of folk magic, effectively a type of ritual exorcism but what makes it interesting to me is that it calls on both the priest's own God - Jesus - as well as the fairy Queen Aoibheall. It also implicates both Aoife, as another Fairy Queen, and the Tuatha De Danann more generally, for possibly setting this spirit on the woman in question. The chant also includes the claim by the priest that he will not hesitate to satirize any spirits who won't help him to banish this leannán sí, an unusual suggestion since one might assume that he would usually resort to calling on his own deity for that.
'Exorcism of a Leanná Sí' is only one example of the way that folk magic, fairy belief, and the dominant religion blended into a cohesive system of practice in early modern Ireland. We may look at this approach and say that it is an attempt to cover all the possibilities, as it were, in assuring that a cure is achieved. Or we may see it as reflecting the multiple cultural threads that influenced people, including clergy, even in the 19th century. In any case it is an important piece of evidence and also a useful charm.
*any errors in my transcribing the Cló Gaelach are entirely my own. I have included the original text for the reader to see for themselves.