As always, I point you to Catholic Culture for more on this feast day, and in particular the prayer of Enthronement:
O Most Sacred Heart of Jesus, Thou didst reveal to the blessed Margaret Mary Thy desire to rule over Christian families; behold, in order to please Thee, we stand before Thee this day, to proclaim Thy full sovereignty over our family. We desire henceforth to live Thy life, we desire that the virtues, to which Thou hast promised peace on earth, may flower in the bosom of our family; we desire to keep far from us the spirit of the world, which Thou hast condemned. Thou art King of our minds by the simplicity of our faith; Thou art King of our hearts by our love of Thee alone, with which our hearts are on fire and whose flame we shall keep alive by frequently receiving the Holy Eucharist. Be pleased, O Sacred Heart, to preside over our gathering together, to bless our spiritual and temporal affairs, to ward off all annoyance from us, to hallow our joys and comfort our sorrows. If any of us has ever been so unhappy as to fall into the misery of displeasing Thee, grant that he may remember, O Heart of Jesus, that Thou art full of goodness and mercy toward the repentant sinner. And when the hour of separation strikes and death enters our family circle, whether we go or whether we stay, we shall all bow humbly before Thine eternal decrees. This shall be our consolation, to remember that the day will come, when our entire family, once more united in heaven, shall be able to sing of Thy glory and Thy goodness forever. May theImmaculate Heart of Mary and the glorious Patriarch St. Joseph vouchsafe to offer Thee this our act of consecration, and to keep the memory thereof alive in us all the days of our lives.
Glory to the Heart of Jesus, our King and Our Father!