McMillan was a member of the folk rock band Spirit of the West, and is a multi-instrumentalist who has played guitars, bass, banjo, trombone, mandolin, bozouki, Chapman stick, piano, and keyboards on the band's albums.
McMillan was a musician in the folk rock band Spirit of the West, playing various instruments like guitar, bass, banjo, trombone, mandolin, bozouki, Chapman stick, piano, and keyboards on their recordings.