this may be old info, but have you seen this?
http://www.m1dst.co.uk/Default.aspx?Page=FreeNAS%20with%20iTunes%20(mt-daapd)&AspxAutoDetectCookieSupport=1
(watch the line break when copying the URL)
He’s got 0.2.4 mt-daapd running on FreeNAS. It would be great to update this to the latest Firefly but I certainly don’t have the skills. Perhaps the author of this could help?