Didn't find the song, but here's a little information:
10,000 Miles

From the film Fly Away Home This lovely piece of music was produced by Mary Chapin, John Jennings and Mark Isham. The song is performed twice in "Fly Away Home" and the second you hear the tune you will be blown away !
Unfortunately the only way to hear Mary Chapin perform this tune is by watching the movie, there was not a soundtrack released for this film, and Mary Chapin has yet to record this traditional Irish tune on any albums, lets hope that someday she will! There is a recording by Mary Black under the title "Fare Thee Well."
This web site has a little information.

Say, could the song you're looking for possibly be Fare Thee Well Marianne? It has the phrases "ten thousand miles" and "fare thee well."
-Joe Offer-