I've followed the instruction in this post that explains how to force login when an authenticated users tries to add items to the cart.

http://www.zen-cart.com/forum/showthread.php?t=169047

It works great, but I want to make one more customization.

The input fields display to unauthenticated users. For example, the user can still put they want 5 or item X. When the click the "Login to Shop" link they get the login/registration page as desired, but the input value is lost.

I think the best solution is to somehow disable the product options input fields for people that are not logged in. How would I do that.

Thanks in advance.