If not, you probably shouldn't be playing with a beta OS ) The install process should be familiar to you.I had to mash F12 while the machine was starting up and then choose 'EFI CD/DVD' in the boot manager. Boot the virtual machine from the Sierra.iso you created, which you'll find on your desktop.Create a new El Capitan (there is no option for Sierra at the moment) machine.Step 2 (Installing in VirtualBox) This is pretty straightforward. hdiutil convert /tmp/ -format UDTO -o /tmp/Sierra.iso.hdiutil detach /Volumes/OS\ X\ Base\ System/.cp -rp /Volumes/install_app/BaseSystem.dmg /Volumes/OS\ X\ Base\ System/BaseSystem.dmg.cp -rp /Volumes/install_app/BaseSystem.chunklist /Volumes/OS\ X\ Base\ System/BaseSystem.chunklist.cp -rp /Volumes/install_app/Packages /Volumes/OS\ X\ Base\ System/System/Installation/.rm /Volumes/OS\ X\ Base\ System/System/Installation/Packages.asr restore -source /Volumes/install_app/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase.hdiutil attach /tmp/ -noverify -nobrowse -mountpoint /Volumes/install_build.hdiutil create -o /tmp/Sierra.cdr -size 7316m -layout SPUD -fs HFS+J.hdiutil attach /Applications/Install\ macOS\ Sierra\ Public\ Beta.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app.Step 1 (Creating a bootable macOS Sierra ISO for VirtualBox):
