There are a number of links of interest regarding the Holy Face Devotion. Below are some websites and articles that are of special interest to me, though I do feel the need to make some general qualifications:
Veronica’s Suffering Face of Christ is the Logical Object of Adoration in the Holy Face Devotion
First, the Veronica Veil image is key to the Holy face Devotion. Some associate other images of Christ with the Devotion, and while they are beautiful and often have compelling stories of their own, the revelations given to Sister St. Pierre and the thousands of miracles associated with the Devotion indicate that the dolorous (sorrowful) Face of Christ is what is being offered to the Father in reparation for sins against the first three commandments; it is the sorrowful Face which is so pleasing to the Father. He is moved by the suffering Face of His Son to have pity for man’s face, disfigured by sin.
More specifically, the Veronica Veil image, even more so than the Shroud of Turin, for example, is the logical object of veneration in the devotion. Veronica was mentioned numerous times in the revelations as a model of consolation to Christ, which we are called to emulate by offering reparation to the Father. According to the revelations, this comprises the greatest consolation to the Sacred Heart of Jesus. (Christ was still living when Veronica offered Him consolation; the Shroud of Turin records the dead, wounded Face of Christ at the moment of the Resurrection.)
The Veronica Veil image is the one that Venerable DuPont used to perform thousands of miracles over a span of thirty years of the Church’s greatest miracle working, earning him the title of “perhaps the greatest miracle worker in Church history” by Pope Pius IX. The miracles were effected through the prayers of the devotion and oil from a lamp burning in front of a hand drawn Veronica’s Veil Holy Face image, which had been touched to the original Veronica’s Veil in the Vatican. This veil itself was the subject of a miraculous event, in that it had become inexplicably “enlivened” for three hours on December 27, 1848, the third day of a Christmas octave exposition.
It is specifically the wounded Face of Christ as object of adoration in the Holy Face Devotion which Our Lord revealed to Sister St. Pierre as “the greatest source of grace, second only to the sacraments.“
The Holy Face Devotion Is To Make Reparation for Sins Against the First Three Commandments, Not the Last Seven
Second, while it is understandable that one would feel inclined to “update” the prayers of the devotion to include the most hideous sins of modern times for which man ought to make reparation, the Devotion to the Holy Face is strictly to make reparation for sins against the first three commandments (from which sins against the remaining seven stem). Moral Law is encapsulated in the ten commandments, but its axis is the first three. The first three have to do with affronts against God, which is the particular object of reparation in this devotion. One is to help bring about right orientation of man to God in the Holy Face Devotion. Right orientation of man to man will follow.
Third, in consideration of the above, I do not necessarily endorse everything in these Holy Face Devotion links of interest, but the information pertaining specifically to prayers of the devotion, its history, and pertinent theological insights are very worth the read.