Open a modal window in joomla with form fields in custom module config

Hi I am developing a module and need a modal window to show a form with some input fields. The entered values should be passed back to the module settings.

What I specifically need is: In the module settings is a field with a button / link beside it which should open the popup. If the user saves the form from the popup the inserted data should be passed back.

What is the correct way to accomplish this feature.

Solution

Thanks your answer was partial useful.

For anybody who like to know how I achieved the modal window and pass back data from it to a main dialog:

I ended up using Fancybox (http://fancybox.net/) which is JQuery and way more flexiable than the Joomla default modal window.

The result can be found here:

general path to project: https://github.com/DHoffm/Responsive-color-google-map
JS: FancyBox can be found in the /js/fancybox folder and JQuery Click Handling can be found in /js/responsive_map_admin.js
PHP: /includes/elements/geodata.php (the code for the modal window can be found at the bottom)