If the machine is running Windows XP you may want to install a program for someone without having to log them off. A simple way is to use the “runas” command line utility to invoke the Control Panel applet Add Remove Programs.
Start > Run… > cmd > runas /user:Administrator cmd (this will prompt you for the local Administrator password and open a new elevated command prompt window)
In the Administrator command prompt window perform the following: control appwiz.cpl (this will open the Add Remove Programs GUI interface)
It is at this point you may uninstall a program or use the GUI to add a program and browse to the installer file.
Note: If you simply want to install the app via command line you can do that as well. Instead of running the control panel applet just execute the installer via the command line. You will get the same results.