Add newsletter signup checkbox in checkout

Does anyone know of a hack or module that allows us to add a checkbox in the checkout process that will automatically sign people up to built-in CS-Cart newsletter feature as a subscriber? The checkbox should always be checked & if customer doesn't want to receive updates, etc. then they can uncheck the box.

Website>Newsletters>Mailing Lists

Edit an existing Mailing List, or create a new one, and check the box for “Show at checkout”.

This will be disabled (unchecked) as default on the checkout pages, but can easily be changed in the templates to be checked as default in /skins/basic/customer/addons/news_and_emails/hooks/checkout/extra_payment_info.pre.tpl - simply remove the {if} statement enclosing checked=“checked” to check the box by default.

Thank you! Appreciate the help.