I believe Fr. Robert Fromageot was professor of Gregorian chant at the FSSP seminary:
About Jeff Ostrowski
A theorist, organist, and conductor, Jeff Ostrowski holds his B.M. in Music Theory from the University of Kansas (2004), and did graduate work in Musicology. He serves as choirmaster for the new FSSP parish in Los Angeles, where he resides with his wife and children.