Q: How can we add Windows 8 Runtime applications to our machines?

A: Windows 8 has the new Windows Runtime (WinRT) environment that supports the new immersive Windows 8 applications (formally known as "Metro-style" applications). The Windows 8 WinRT applications are typically installed via the Windows Store; however, an organization's line-of-business applications can also be installed in a process known as side-loading. To side-load applications, you must enable the Group Policy setting Allow all trusted applications to install  under Computer ConfigurationAdministrative TemplatesWindows ComponentsApp Package Deployment and either of the following must be true:

Product activation keys for non-Windows 8 Enterprise editions joined to a domain will be available for purchase by organizations.

After the above conditions are met, you can use the Add-AppXPackage cmdlet to install the appx files that comprise the Windows 8 runtime applications. Full details can be found at the Microsoft article "How to Add and Remove Apps."