Argentarius,

There are a few threads hereabouts which begin to address your question. Kathy Pluth has written a hymn text (or more) and Charles Giffen has written at least one tune. These are probably not in WLP's stable.

People more familiar with WLP will be able to point you to specific not-awful music and text.

From the perspective of a member of a team, though, music aside, I have several different suggestions, entirely serious. You could spend extravagantly in the next 24 hours, trying to pull together the resources you need, and respond to any queries about why you're spending so much with a simple thought: you wouldn't be doing this, except that you got 36 hours notice to pull this together; or, you could draw entirely from the Graduale Romanum, at least if you read the chant well, and sing those Propers for the Mass of the day, responding when someone complains that you had to rely on what you could do quickly.

Music shouldn't be thrown together, and someone else's lack of planning doesn't make your crisis.

[Now I'll go nurse my sore head].