This is comprehensive guide to create Mac OS X Bootdisk installer. The guide uses VM but it should work the same on physical disk.
Tag: Mac OS X 10.10 Yosemite
Admin Scripts: Mac OS X – Installer Conversion (DMG to ISO)
Mac OS X can be freely downloaded from Apple Mac Store (in DMG) but it is not bootable. Hence, to install Mac OS X from scratch is not possible using DMG. The scripts is written to convert downloaded Mac OS X from Apple Store into Bootable ISO file.