Good question.. The old store locator and the gravity form was on the same page.The gravity form has an HTML section where the output was passed too. I believe the results where passed to an array which could be called via the nearest_stores hook.
Alternatively I have been trying to embed the shortcode for this plugin in the HTML of the gravity forms however this is not displaying the map at all or showing results.
Can you think of a better way to do this?