Use the RunAs: command
http://technet.microsoft.com/en-us/library/cc772672.aspx
Actually, its kind of lame that they wont let you embed the password with that tool. In this thread, techies describe possible solutions to this problem and other tools you could use. Good Luck.
http://blogs.msdn.com/oldnewthing/archive/2004/11/29/271551.aspx