So, assuming you have a relatively recent Mac, the first thing you'll need to install Windows 8 Preview Release via Boot Camp is, not surprisingly, a copy of Windows 8 Preview Release, which Microsoft is providing at the cost of only a valid email address and your immortal soul. Since we've already determined that you're using a recent Mac, you'll want the 64-bit release. Remember to make note of the activation code. Yes, I said "activation code."

Hey, whoa, whoa. the one who wanted to use Windows, remember? Don't shoot the messenger.

Once you've downloaded the disk image, open Disk Utility on a Mac with an optical drive and mount the image in the sidebar. Click on the disk image and burn it to a blank disk. It's possible to use a USB disk image, but that also requires an existing Windows install as well as .

Now get ready to lose some hard drive space! The 64-bit version of Windows 8 requires at least 20GB of disk space; the 32-bit version 18GB. Launch Boot Camp Assistant. On the first screen, uncheck the option to download the latest Windows support software from Apple, and check the option to install Windows 7. (Yes, Windows 7--as of this writing, Apple has not yet updated Boot Camp for Windows 8.)

Then select how much disk space you want to allocate to the Windows drive. Unlike partitioning a drive using Disk Utility, this process won't wipe your existing data; it'll just allocate a section of your free space for Windows. (If you want to reclaim it later, you can run Boot Camp Assistant again to remove it.) Put your burned Windows 8 install disk in the drive and click Install.