Can I force returning users to accept a Terms of Service?

I have a WP MS (3.5.1) and BP (1.7) network with a main site for WooCommerce, one child site for BP functionality and currently one child site for blogging.

I would like to add a Privacy Policy, Terms of Service and Medical Disclaimer policy to the site and force all of my existing users to agree to it when they log in. And, of course, any new users who register would have to agree to it as well. Those who have already agreed to it would not be prompted again. Do you know of any plugins that can do this? I've installed the WPMUDev Terms of Service plugin but I don't think it can force returning users to accept the ToS.

I would also like to have some custom text on the register page that users had to agree to specifically that wasn't buried inside a ToS or Privacy Policy that most people don't read anyway.

How can I accomplish this?