To use 66 try the following:
cat > /etc/66/init-voidlinux << EOF
#!/usr/bin/execlineb -P
66-boot -m -b "Void Linux"
EOF
chmod +x /etc/66/init-voidlinux
sed -i '/GRUB_CMDLINE_LINUX_DEFAULT=/s/"$/ \
init=\/etc\/66\/init-voidlinux"/' /etc/default/grub