One of the antiphons in the revised Missal translation is:

Let us change our garments to sackcloth and ashes,
let us fast and weep before the Lord,
that our God, rich in mercy, might forgive us our sins.

Which corresponds to:

IMMUTEMUR habitu, in cinere et
cilicio: jejunemus, et ploremus ante
Dominum: quia multum misericors
est dimittere peccata nostra Deus noster.

in the Graduale.

So, for the fun of it, I tried adapting the chant for the Latin version to the text of the English. The result is attached. Let me know what you think. Don't worry, I have thick skin.

I will also note that I did it using the on-line Gregorio editor available here, which Adam Bartlett mentioned a while back. While I'm proficient using Gregorio on my Ubuntu machine, this on-line app is perfect for composing because it gives you real-time feedback.