Purchase and download Lion from the Mac App Store on any Lion compatible Mac running Snow Leopard.
- Right click on the “Mac OS X Lion” installer and choose the option to “Show Package Contents.”
- Inside the Contents folder that appears you will find a SharedSupport folder and inside the SharedSupport folder you will find the “InstallESD.dmg.” This is the Lion boot disc image.
- Copy “InstallESD.dmg” to another folder like the Desktop.
- Launch Disk Utility and click the burn button.
- Select the copied “InstallESD.dmg” as the image to burn, insert a standard sized 4.7 GB DVD, and wait for your new Lion Boot Disc to complete.
With this disc you can boot any Lion compatible Mac, and install10.7 just like you installed previous version of Mac OS X. You can even use Disk Utility’s Restore function to image your Lion boot disc image onto a external drive suitable for performing a clean install on a optical-drive-less MacBook Air’s, or Mac mini server.