Last week Joel McNeely wrote in his blog about his experience composing and recording the soundtrack for the Tinkerbell movie. Included in that is a huge amount of information about Máiréad's contribution including how they worked on her part in the score while she was on tour with CW.
http://web1.joelmcneely.com/blog/music/2008/10/the_tinker_bell_movie_1.phpaislin