From a reddit page, untested by me, but could be worth a try:
# tools:
brew install dvdauthor dvdrtools
# Convert to MPEG-2
ffmpeg -i input.file -threads 16 -aspect 16:9 -target ntsc-dvd out.mpg
# Demux into VIDEO_TS/AUDIO_TS structure:
VIDEO_FORMAT=NTSC dvdauthor -o directory -t out.mpg
# Create table of contents IFO
VIDEO_FORMAT=NTSC dvdauthor -o directory -T
# Create ISO
mkisofs -dvd-video -V VOLUME -o out.iso directory/
# Burn
hdiutil burn out.iso