Fr Christian de Cherge was the prior of the Cistercian monastery at Tibhirine, in Algeria, and was one of the seven monks of that monastery who were killed in 1996. The story of the events at the monastery is the subject of the film Des hommes et des Dieux. I am currently reading - extremely slowly - a study of Fr de Cherge's theology and experience of Moslem-Catholic dialogue. A chapter of this book is dedicated to "The reading of the Koran". For Christian de Cherge, the reading and study of the Koran formed part of his particular vocation in the Church; it arises from his specific charism rather than because he felt that it was something every Catholic should do. However, his understanding of what this involved is very carefully articulated, and very nuanced.
Christian de Cherge frequently wrote that he underook lectio divina with the Koran. When this is put into the context of the monastic life of a Cistercian community, it is important to realise that this was not a replacement of meditation on the Biblical texts by meditation on texts of the Koran. It should perhaps be more accurately seen as something undertaken alongside the more conventional Christian lectio divina. Fr de Cherge characterised the Koran as
..that which the other has received for their own ("en propre", in the original French) to support in them the taste for God...Christian's articulation of the place that the non-Christian religions have in the design of God, and in relation to Christian faith, is quite careful. In his thought, and in his lived experience, he is not able to discern what is that design, but he looks forward to its being revealed to him when he enters heaven. So when he writes of the Koran as being "received" by Moslems he does not assert that the Koran is a supernatural gift to them but is instead recognising that in the mysterious disposition of God it is something that they possess for their good.
Christian is also clear that the Koran is a book that belongs to Moslems as their own proper possession and that, though a Christian might read, study and meditate upon it, they should not appropriate it. This has an aspect of respect towards the properly Moslem text; but it also says clearly that the Koran, as the sacred writings of the Moslem religion, should not be put on the same footing as the Bible, the sacred writings of the Christian religion. The two scriptures should not be confounded with each other, something that can be said from both the Christian side and from the Moslem side. In a very nuanced phrase, Christian could consider the Koran as having "an original link to the Totally-Other", though he is not able to fully describe the nature of that link. But he never wishes to give to the Koran and the Bible any sense of equivalence.
This has an implication for the way in which Christian de Cherge uses the text of the Koran and the text of the Bible. He reads them "side-by-side", and does not compare and contrast them to give one text a value over and above the other. Where he uses a text from the Koran that has a parallel to a text from the Bible, Christian in effect comments on both of the two texts, using the Koranic text to provide a comment on the Biblical text and vice-versa; he lets the two texts co-respond to each other. In this way he is neither offering a Christian interpretation of the Koran nor a Koranic interpretation of the Bible. The French title of a section of this chapter captures this in the word "L'intertextualite" - inter-textuality.
Christian writes that he experienced at times a sense of hearing the Word as he meditated upon the Koran, a charismatic sense of the presence of God in the words that he was reading. Again, to make sure that we understand this essentially charismatic gift - Christian is in no way asserting that the Koran is a supernatural revelation, only that it has enabled him, in the context of his unique vocation in the Church, to experience the Word of God - we have to place it in the context of Christian's understanding of the place of the Moslem religion within the design of God referred to above. Christian can write that the Moslem and the Christian have in common an experience of the Word of God; but, for the Christian, that Word is incarnate in the flesh and blood of Jesus Christ, whereas, for the Moslem, that Word is the written word of the Koran. For both, the Word is One and Unique.
What would Christian de Cherge's answer be to the question posed in the title of this post? If the question means using the Koran as a source of texts for use in Christian prayer, and in particular in the Liturgy, I think he would answer "No". This would represent the appropriation of the Koranic text by the Christian believer and, from the Christian point of view, an inappropriate substitution of that which is properly Christian (the Bible) by that which really belongs to Moslems. If the question means that Christians should gain an experience of the Koran as part of their engagement in Moslem-Christian inter-religious dialogue, then the answer might be "Yes".