Demo:
http://opencart.progroman.ru/demo/geoip/

The module adds popup "Login" and "Registration". By clicking on the proper link the user stays on the same page, there is a form the pop-up window.

In the case of successful operation, the user is authenticated, and the page is refreshed.

Popup is made based on jQuery UI, which is used in OpenCart by default. Theme for dialogs can make his or choose from ready: http://jqueryui.com/themeroller/#themeGallery

vqmod not required, not replace files.