How to build email list using CPAbuild?

With Cpabuild templates on WP or blogger, some of the premade community templates have an email submit field, but then the email is just wasted as it's not registered in a database.
The prebuilt template cannot be modified as far as I know on WP, it's just a redirect link.
Any idea on how to build an email list off of it?

interested in this too

You need two things : PHP script that inserts stuff (emails here) in database. Can be standalone or made as Wp plugin, depending on your skills. Second, a bit of Javascript in the page, that reads email input with an onsubmit function and sends it via Ajax to the PHP script.