Cirdan from Der Herr Der Ringe emailed The Official Loreena McKennitt Website about her rumoured involvement (reported here yesterday). Here’s what their response was:

Dear Cirdan,

Thank you for your inquiry concerning Loreena’s involvement in the movie
“The Lord of the Rings”. No, at this point in time, Loreena is not
involved in any way with this production. Sorry!

Regards,

Suzanne Steinacker

Hmm… makes me wonder why Ms. McKennitt answered the question in the online chat precisely the way she did.