To create a bootable USB drive from a DMG file on Windows, you will need to have the right utility. The macOS installer file is large with approximate size of 6 to 10GB depending upon the. Make Windows Bootable USB Mac with PassFab 4WinKey. Steps to create a macOS Siera beta boot disk. First, let us look at how to create a bootable drive using Terminal. You can either use Terminal or get the job done through a free software like Recoverit to do it for you. There are two ways of creating a bootable copy of the installer. How to Create a Bootable Drive Using Terminal. Go to the Microsoft official website and download the free ISO file for.