http://www.perlmonks.org?node_id=991325


in reply to Re^4: Calling an executable and entering login credentials
in thread Calling an executable and entering login credentials

You can try Win32::GuiTest, it seems it's able to send clocks and keystrokes to windows. Also you can use AutoHotKey or AutoIt to write a credentials-entering program, but this is not Perl.
Sorry if my advice was wrong.