I read your post again, and you can probably achieve similar results doing something much easier. Put a shortcut to MT4 in you Programs> STartup folder on the start menu. You can navigate there by right clicking the start button and choosing explore. This will require that user to automatically log in before it will work.

You can also add it to the registry,
HKLM\Software\Microsoft\CurrentVersion\RunServices
The entry would be "C:\Program Files\MetaTrader 4\terminal.exe" or whatever your path is. THis would not require the user to log in but it is rather advanced.