prompt for Username without Password?

[Kerry]

    Is there a way to define a protection rule that will cause the user to be
prompted for only their Username (which in our case would be a student id
number) without prompting for Password?  If not, what is the best way to handle
validating a population of library patrons?  Using last names for Username 
won't work, since so many are non-unique.  I could reverse it (use student id
numbers for "usernames", and last names as "passwords"), but this seems like 
it will create a great deal of confusion unless there is some way to control
the prompt text ("Username:", "Password:") from the server end.

        Thanks,
             Kerry Bouchard, Automated Systems Mgr.
             Mary Couts Burnett Library, Texas Christian University
             K.BOUCHARD at TCU.EDU