External Email - Use Caution
Go into your $FREESURFER_HOME and create a backup of your existing freeview app (this may require sudo access):
cd $FREESURFER_HOME cp Freeview.app Freeview-backup.app
Download the dev, standalone freeview tarball from here
Untar freeview within your $FREESURFER_HOME (this may require sudo):
cd $FREESURFER_HOME tar -xzvf /path/to/freesurfer-darwin-macOS_HighSierra-dev-freeview.tar.gz
IMPORTANT: If you are replacing freeview in a freesurfer release LESS than 7.0, then you must also remove the line "source $FREESURFER_HOME/sources.csh" from the $FREESURFER_HOME/bin/freeview script