Hi John
Firstly huge congrats again.
Secondly, regarding this credit card authorisation thing. I don't know about other airlines, but I have done something similar with Etihad. It does say on their website, that if the card is not available, then a copy of both sides, with your signature authorising it's use will suffice. You could mail her this and she could get it printed out.
What however I would recommend doing, is phoning their customer services, with her booking reference, and explaining what you've done. They will then be able to tell you what you need to do. You may have to go to the airport, with her printout of her booking, and of course your card, and they can then authorise it over their systems - which is of course obviously linked worldwide to their central system. They might also have a different easier thing to do. This must have happened before, so there will be a way