Its been a week now since Apple released OS X Yosemite Developer Preview and with all the new features and specially the overhaul in the design, there’s no point for users like me to not to test the build. Unfortunately, I couldn’t update to OS X Yosemite because of Hackintosh problems but if you’re a Mac user or have a decent Hackintosh setup, you can easily upgrade to Yosemite Developer Build without any problems.
One way of upgrading is to install OS X Yosemite over your current installation, which is not at all recommended as Yosemite is currently in unstable stage, and even if significant number of the things are working in Yosemite, you should not install it over your current setup. The other way for testing OS X Yosemite is create a new partition on your Mac or use an external drive and install OS X Yosemite in the new partition, this way, you’ll have access to Mavericks as well as Yosemite and you can get rid of the Yosemite partition anytime after testing.
Either way, you’ll need the OS X Yosemite app which you can download from your Apple Developer account or from Apple Beta Seed program site if you have signed up earlier. But, for installing Yosemite on an external drive or a different partition of your Mac, you’ll need a bootable USB of OS X Yosemite.
You can create bootable USB installer for Yosemite using the traditional method which involves complex steps like mounting different images and copying the contents manually to the USB drive. But, there’s also a simpler way of making Yosemite installer. There’s a tool called MacPwn which simplifies the process of creating bootable USB for Yosemite.
Before getting started, just plug-in the USB drive and then open Disk Utility from Utilities folder. Now select the USB drive, move to partition tab, select 1 Partition from the drop-down and click on “Options” button at the bottom and select “GUID Partition Scheme” option. Once done, format the USB drive.
You can download MacPwn here. To create the USB installer, you just need to have the OS X Yosemite Developer Build app file in your Applications folder, and then you need to start the MacPwn app. MacPwn is basically created for Hackintosh based installations, but it works for real Macs too. Once you open the app, follow the screen. When you’re asked to select the Destination, select the USB Drive(should be at least 8GB) which you want to make the installer and you’ll reach a screen with “Customize” button at the lower left, you need to click on that and uncheck all the options, because those are for Hackintosh installations. So, once you uncheck everything in the Customize screen, you just need to finalize the setup and it will start creating your USB. It will take some time as it will do all the steps automatically, and it will also notify you through Notification Center notifications. Once done, you can use the USB to install OS X Yosemite anywhere.