DevxExec

Devxexec is the tool the allowing running processes under different user accounts without knowing the password. It is even possible to run a process under domain account without specifying its password! You can use Devxexec to run a process under SYSTEM, NETWORK_SERVICE, TrustedInstaller in an interactive session. Devxexec has command line interface and in can run in mute mode so it's possible to use it from your own application.