As in the UI, so on the commandline.
SCVMM 2008 Cmdlet Reference is now available in the download center, and contains all the Help topics for the VMM 2008 cmdlets in one handy DL. Everything you can do using the VMM Administrator Console to administer your Virtual Machine Manager environment, you can also script using the cmdlets in the Windows PowerShell – Virtual Machine Manager command shell, which is an administrator-focused command-line shell.
This topic contains sample commands that you can use to get Help in the Windows PowerShell – Virtual Machine Manager command shell or in Windows PowerShell.: Using Cmdlet Help