If the music you want to use for a metronome riff has been saved as a standard MIDI file (with one track only), just drop it into the Metronomes Folder on your hard disk. It then shows up in the Custom Riff pop-up menu in the Metronome command in the Setup menu.
If not, just select the music in the Graphic Editing view or Notation view and then choose Save as Metronome in the Region menu. Be sure to only select one player's worth of music. Metronomes cannot consist of more than one player.
