The FSSP and Our Lady of Guadalupe Seminary provide training for priests in the ancient Tridentine liturgy for all of North America, and chant is an integral part of their education. They also host workshops on chant for lay people. Site has many mp3 files.
http://www.fssp.com/main/chant.htm
Brief historical overview of the liturgical music of the Norbertine Order.
http://www.premontre.org/SubPages/Loci/ZZZLocalSites/LSClaymont/Premonstratensian%20Rite.html