Hi, iamjohnmorgan:

For context, is this an old-rite Confirmation or according to the current edition of the liturgical books?

The Propers should be that of the Sunday - Pentecost XXI.

For the Mass itself, it is very little different than a normal Sung or Solemn Mass... you'll have the same component parts. The challenge will be recognizing where they occur in time as everything will look differently in the sanctuary than what you would normally be accustomed to (as far as the placement of ministers, servers, etc.). One key example would be the intonation of the Gloria, which occurs from the faldstool, not from the altar.

The only things that I can remember being different in terms of what you sing are that the invocation Dominus Vobiscum is different for a bishop (so your response is the same, but he will instead intone Pax Vobis) and the versicles (for which you will sing the responses) before the Last Blessing, which is itself sung.

The versicles and response the Last Blessing are found in the Liber Usualis around page 111.

In answer to your original question about Ecce Sacerdos, it is not anticipated rubrically (this is not the Ordinary making a pastoral visit, but a visiting Bishop simply administering Confirmation), however, there is nothing to preclude you from using Ecce Sacerdos either as a motet or as chant during some appropriate time.

Ceremonially, some places may have the bishop vest / divest in the sanctuary - which you may want to cover with music (like Ecce Sacerdos). Other places do not do the ceremony associated with vesting / divesting and the Bishop processes in and out already fully vested. So that will be one thing for certain to discuss with your pastor.

However, you will still need to account for the time between the Mass and the Confirmation. The only thing rubrically appointed to be sung is the Confirma Hoc, which you can either sing in parts or in chant as in the L.U. on pp. 1844, 45. This would follow the confirmations while the Bishop is washing his hands, and includes the versicles and prayers as indicated. It is not uncommon to sing Veni Creator or equivalent before the confirmations... so another question for the pastor would be whether the Bishop would like to intone that and to sing the responses that follow.

For the confirmations themselves, it can be done either in silence or with suitable vocal or organ music during. I've done it both ways.

The questions I would suggest minimally covering with your pastor...

• The order of ceremonies. Will the Mass be followed by Confirmation? Will they be completely separate - e.g. Mass in the AM, Confirmation in the PM?
• What is the plan for vesting / divesting?
• If the Confirmation follows Mass, how will that work logistically (so you can form an idea of timing and what you'll need to do musically)?
• Will the Bishop intone the Veni Creator and sing the versicles following before administering the Confirmation?
• Will there be music during the Confirmations, or just following as the Confirma Hoc? What cue for starting the Confirma Hoc (obviously depends on whether you'll do one in parts or the chant version)?
  
• I would suggest that you attend the servers / ministers practice (at least one as long as it is comprehensive) so you have a better understanding of the flow of the Mass. From the meeting and your practice session, you'll be able to map out the remaining music, including your decision of whether or not to use Ecce Sacerdos.

Best of luck!