Apparently, since 1998, a special prayer is added to the Catholic ordination rite administered to Anglican convert clergy, by order of the CDF; it is said before the Litany, and does not replace the ordination prayer itself. I found this quoted over at Damian Thompson's blog by one of his commenters:
Oratio ad gratias agendas pro ministerio ab electo in Communione anglicana expleto[Prayer for giving thanks for the former ministry of the ordinand in the Anglican Communion]Deinde omnes surgunt. Epsicopus, deposita mitra, stans manibus iunctis versus ad electum dicit:[Then all rise. The bishop, having doffed his mitre, standing with joined hands, facing toward the ordinand, says:]N., the Holy Catholic Church recognizes that not a few of the sacred actions of the Christian religion as carried out in communities separated from her can truly engender a life of grace and can rightly be described as providing access to the community of salvation. And so we now pray.Et omnes, per aliquod temporis spatium, silentio orant. Deinde, manus extensis, Episcopus orat dicens:[And all, for a certain space of time, in silence pray. Then, with extended hands, the Bishop prays saying:]Almighty Father, we give you thanks for the X years of faithful ministry of your servant N. in the Anglican Communion [vel: in the Church of England], whose fruitfulness for salvation has been derived from the very fullness of grace and truthentrusted to the Catholic Church. As your servant has been received into full communion and now seeks to be ordained to the presbyterate in the Catholic Church, we beseech you to bring to fruition that for which we now pray. Through Jesus Christ, our Lord.Populus acclamat:[The people acclaim:]Amen.