Ok, I can see where my question might take on weird aspects as to why I asked, so lemme explain the reason for my question:
I'm trying to put myself in this person's shoes and determine how I would go about doing this recording, with their equipment.  But I have certain priorities:
1.  What the hell am I getting myself into?  
2. What is the purpose of this recording?
3. How can I pull this off and make myself look good?
Those 3 factors are where the bulk of my question comes from.
So, let's look at each part:
1.  What the hell am I getting myself into?
I need enough information to make some decisions about the recording.  Is this gonna be a one-shot recording in front of a live audience, or will we just be using the church piano, so I'll have time to try various mic positions, and do several recordings if needed?  Will we have several days to do the project, if we need them?  Can I hear the pianist playing the piece on that piano, before we actually try to record it?
2. What is the purpose of this recording?
If it's for the artist's personal scrap book, it's less of a big deal.  If it's for sale to church members and the artist's friends, it's a little bigger deal.  How big is the congregation, and how many friends?  If it's for distribution and they plan to make a 1,000 copies of this recording, that's a whole 'nother thing.
3. How can I pull this off and make myself look good?
As the stakes go up (depending on answers to 1 and 2), I want more control of the situation.  If the artist wants live (with an audience), that's fine, but I want another recording with NO audience.  I'll use the intro and applause from the live show and add it into a pristine performance I already have in the can. If the live show comes out "better", I'll use that.  
I aready have a pristine non-live performance tucked away, and I'm now familiar with the venue's acoustics and the piano sounds.
Basically, the choices are simple:
If it's live with an audience, you have almost no control of anything. The best you can hope for is no coughers or screaming babies, and a decent, but not great, recording of the event.
For any other recording situation, you hafta take control, especially take control of any available time.  If it's gonna be a serious recording, do it right, or don't do it at all.