Pass authentication information in a batch file

I’ve googled this and seen a lot of ways to pass the info through for a logon script, but I have a different sort of question.

I have a program launching batch file using commands of this sort:

start /d “C:\Program Files\Microsoft Office\OFFICE11” WINWORD.EXE

Let’s pretend Word would prompt for a username and password after starting. Does anyone have an idea on how to put the username and password in via an argument?
I’m afraid this will only be available if it was designed into program, but I’m sure there are wiser folk than I on here.
Thanks in advance for your help!
Cheers,
A.