hfs-bless / Booting into MacOS / Windows directly from Ubuntu (triple boot, MacPro 4,1 -> 5,1)
I know it's an old thread but for your information: you can still download mactel-boot .deb package from this link http://ppa.launchpad.net/detly/mactel-utils/ubuntu/pool/main/m/mactel-boot/mactel-boot_0.9-1~xenial_amd64.deb (Xenial version). It's install smoothly in Ubuntu 2018.04.3 LTS correctly and, apparently, works.