Run As Command in Windows 2000/3 & XP
Runas
Allows a user to run specific tools and programs with different permissions than the user's current logon provides.
Syntax
runas [{/profile|/noprofile}] [/env] [/netonly] [/smartcard] [/showtrustlevels] [/trustlevel] /user:UserAccountName program
Examples
To start an instance of the command prompt as an administrator on the local computer, type:
runas /user:localmachinename\administrator cmd
When prompted, type the administrator password.
To start an instance of the Computer Management snap-in using a domain administrator account called companydomain\domainadmin, type:
runas /user:companydomain\domainadmin "mmc %windir%\system32\compmgmt.msc"
When prompted, type the account password.
To start an instance of Notepad using a domain administrator account called user in a domain called domain.microsoft.com, type:
runas /user:user@domain.microsoft.com "notepad my_file.txt"
When prompted, type the account password.
To start an instance of a command prompt window, saved MMC console, Control Panel item, or program that will administer a server in another forest, type:
runas /netonly /user:domain\username "command"
domain\username must be a user with sufficient permissions to administer the server. When prompted, type the account password.
Reference- Microsoft Website