How to add a checkbox to the "Never see this message again"

HI there!

I want to change two things on the Popup
http://nomadmx.com/?page_id=43

1- I want the "Never see this message again" to be in spanish

2- Instead of underlined as a link I want it to be a checkbox, Then if they check and then click the "Acepto" button they wont see it again!
The "acepto" button is linked to the same page http://nomadmx.com/?page_id=43

Thanks so much in advance