I have used this on many occasions to run-up IE under different user credentials.
Below is a code snippet to use the the “RunAs.exe” utility.
C:\Windows\System32\runas.exe /user:email@example.com /savecred “C:\Program Files\Internet Explorer\iexplore.exe”
I normally create a batch file on my desktop to execute this command line. Use the switch /savecred to prompt for the password and once entered it will save it for latter use.