Preinstallation Environment Command-line
In DISMTools 0.7 and later, the Preinstallation Environment allows you to load Command Prompt by pressing C at the main menu:
From this environment, you can run any command, including Administration Scripts included with this Preinstallation Environment, like you would in a regular Windows PE system. To learn more about Administration Scripts, see the Administration Script Reference page.
The environment will restart automatically after 72 hours (3 days).