The Church of S.Maria in Domnica was full for the taking posession by its new Cardinal Titular, William Cardinal Levada. Parishioners and Americans mixed to welcome the new holder of this title.
The ceremony itself is quite simple - Cardinal Levada arrived at the Church in choral dress at 5pm. He was greeted at the door of the church by the Pastor who offered him a cross to kiss and holy water with which to bless the faithful.
He then processed to the Blessed Sacrament altar and knelt there in prayer for a few moments. Then he retired to the sacristy and vested for Mass. 
Then, along with the servers (from the North American College), concelebrants (including several bishops and Cardinals) and two American deacons he re-entered the Church to celebrate Mass.
After the opening greeting, the Bull appointing him to the Church was read in Italian by the pastor of the Church and in English by the Cardinal's secretary, Fr Stephen Lopes.
Then, Mass progressed as normal in Latin, with readings in English and Italian. I'm not sure who the choir were - I think I recognised one or two CDF officials amongst them. The mass setting used was the delightful 'Missa Dixit Maria' by Hassler. (Mental Note - Get a CD of this.)
The Cardinal preached simply in (workmanlike) Italian and in English, particularly focusing on the church's link with St Laurence and the Holy Father's presentation of the role of charity within the Church in Deus Caritas Est. 
The last man in Levada's office to hold the title of S.Maria in Domnica was Alfredo Cardinal Ottaviani. Henri Cardinal de Lubac also held that title.