Here is a suggestion
Since the purge latin music books which once filled the parish choir loft along with the loft itself are no longer available and replaced with approved missalettes containing anything but .
To encourage the use of this and other liturgical hymns it would be helpfull if one could post the music along with the latin lyics. So those (including myself) could pass it on to their choir masters.
The Latin is in the link provided by Monsignor Pope. I don’t know what the LM hymn melody means, but I’m sure your choir director dos understand that terminology.