You might need to build your own form but I think you could use the Win32 API function LogonUser(). I've not done this before so I can't say whether this will work or not - for example I can't say what might happens to the system if the userid / password is incorrect. Anyway I hope this function at least points you in a useful direction.

DECLARE INTEGER LogonUser IN advapi32;
STRING cUsername,;
STRING cDomain,;
STRING cPassword,;
INTEGER nLogonType,;
INTEGER nLogonProvider,;
INTEGER @ nToken