I would think that you could do something with the piano acc. of a choral version, or add chords and embellishments to the Guildimann version. One of the things I love about those books is that you can personalize some of the wonderful old music that is hard to find elsewhere.
Thank you for the info. I stink at arranging but I guess i’ll give it a shot. Do you happen to know of any other songs written in this style? I researched the song a bit and found that it is in what is called the villancico style. I love the sound of the song with the main theme and distinctive chorus. The source I found did not mention other songs in this style though!