I started writing something polyphonic for the antiphon O Sapientia, but a section of it took on a life of its own, and I split it off into another piece, which became this Veni Emmanuel setting. This piece is still something of a work in progress. I think in its present form, it could be appended to the chant as a recapitulation, provided the chant is sung in F-minor (or this pieces is taken down a half-step to E minor).

Free PDF and electronic playback are available at the following link, in the hope the piece may be of use:
https://www.catholicliving.net/veni-emmanuel/