Are you a registered developer with Apple? Do you want to try out Mavericks without risking your entire Mac to a potentially wonky version of OS X? I haven’t seen any major issues, yet, but that doesn’t mean that mission critical softaware you rely on will work in Mavericks beta.
So, here’s the solution. Boot up from a USB stick that has been configured as a bootable OS X Mavericks drive. Here’s how.