Very good to know. So if I ever have to emergency baptism someone, I should first tell them about the Incarnation and the Trinity. How much to they have to know/accept?
My opinion is, you'd ask the person
1) Are you a catholic? If they say yes, then you'd ask if they want a priest. In an emergency, you'd ask them if they want to say an act of contrition with you.
2) If they aren't a catholic, then you ask them if they are baptized.
3) If they are baptized, then you ask them if they want to say an act of contrition.
4) If they aren't baptized, then you'd ask them if they know that that is? Do they want to become a catholic?
5) If yes, then you'd ask them:
a) Do you believe that Jesus Christ was born into this world to save us from our sins and to start a Church?
b) Do you believe that Jesus Christ is the son of God, and also part of the Trinity - the Father, Son and Holy Ghost?
6) If they know about these truths, then you could baptize.
7) If they don't know, then you could explain it to them, (depending on the time the emergency allows), and then baptize.
If it's a true emergency, then you'll have to pray and go with what the Holy Ghost inspires you.