Windows To Go is a new feature in Windows 8 that lets businesses to have a full corporate environment that will boot from a USB drive. Once the instance of Windows 8 is booted it functions and is controlled by standard enterprise management tools such as SCCM and Active Directory group policies. Work at home and disaster recovery are the primary use cases as Windows To Go can transform any PC into a corporate PC with your application stack, all on a USB drive. Windows To Go is also perfect for trying out Windows 8 on your primary machine without destroying your current OS.
To begin you will need the following:

32 GB or larger USB Drive (It can be a USB Hard Drive)
A Windows 8 PC to build the USB drive on.
Windows 8 DVD ISO.
A copy of Imagex.exe from the Windows 7 Automated Installation Kit installed on Windows 7 or XP. ImageX can be found in C:\Program Files\Windows AIK\Tools\amd64 or C:\Program Files\Windows AIK\Tools\x86.

Creating the Windows 8 To Go USB Device:

Windows To Go requires a specific partition setup in order to function. We will use diskpart to create the new partition setup. Launch an administrative level command prompt from the Start Screen.
Make sure that your USB Drive is plugged in and then type in diskpart and hit Enter.
Then list the available disks by running “list disk” and you should see your usb device.
Select your USB drive by typing “select disk #” and hit Enter.
Clean the partitions on the disk by typing “clean” and hit Enter.

Now create the partition by running the following command:

create partition primary

Select and format the new boot partition by running the following command:

format fs=ntfs quick
Set the partition active by typing “active” and hit Enter.

Exit Diskpart by typing Exit.

Now double click the Windows 8 ISO you downloaded to mount it in Windows 8. Browse to the ISO files in Windows Explorer and copy \sources\install.wim to the same folder as you copied Imagex.exe.

Identify the drive letter assigned to your USB drive by Windows Explorer and run the following command from the folder that contains Imagex.exe and install.wim:

imagex.exe /apply install.wim 1 d:\

Replace d with the drive letter of your USB drive.)

Once the image has applied you need to setup the boot record on the USB Drive. At the administrative level command prompt run:

bcdboot.exe d:\windows /s d: /f ALL

(Replace d with the drive letter of your USB drive.)