Data Entry Form With Log In

I have a form for data entry. I would like my users (over 250) with google app accounts to be able to authenticate and enter data into the form. This would be a yearly thing were they should be able to see last years entry and make any changes or updates.

These users would have no reason to use zoho for any other reason.

I have Zoho with it using my Google apps account for authentication. We have the academic (enterprise) version of Google apps. How can I best have the users log in and access this? I would not like everyone else in the world to enter data.