Don't
Good information Stephen.
(None of the following information is given as legal advice and should be treated with extreme caution. I am not a lawyer and make no claims to specialist knowledge. Anyone acting on this advice, without taking proper legal council would be very foolish.)
However, a good basic rule for any aspects of film making is
"Unless you have a written and legally binding contract for it, from the script, to the music and even the performances DON'T use it."
This means no adapting other people's book's, using thier characters, using their songs, music, drawings etc., without a negotiated contract.
A UK company (not us), got verbal permission from a member of a signed band to use their music, only to discover, in court, that both the publishing company and the record company owned the rights to the music, not the musican. The settlement figure was fairly substantial.
Another area to be careful of is sound-a-likes, where you record something that is a "tribute" to the original song. It used to be true in the UK, that providing you changed every 7th note, you couldn't be sued. However, that law changed about 5 years ago and now, if the song is clearly recognisaible as having derived from the original, you may get sued sucessfully.
To be perfectly honest, media law is a massive subject and I would recommend any city with a good collection of film makers should to try to persuade a good media lawyer to come out and do a seminar for you.
We've done this before for groups of film makers in the North East of England, the lawyer seeing it as a way of generating new contacts and therefore not charging for the presentation.