Secure web form for outside Yale use

Is there any way I can set a username and password for the Boulder School feedback form (or any form on this site)? Most of the people using the form are from outside Yale and so CAS log-in will not work. Currently, I send the link to the form to the participant list and do not link to the form on the web site. I would like to be able to have a link to the form available so that I can send an email but also have a link that people can access through the school site.

Thank you,
Daphne