Got the job done !

Worked great on my wordpress 4.1 install for my needs which is to display the warning only on the homepage.

There were a few minor concerns in the settings and behavior of the plugin though such as the opacity settings only allowed at 1.85 or 0.85 and, background image not displaying.

However i did not rate it lower for this as it can be solved with adding a bit of CSS:
.cwv3.dialog-overlay{
background-image: url(“/wp-content/uploads/pinky.jpg”);
background-repeat: no-repeat;
background-position: center top;
opacity: 0.98;
-moz-opacity: 0.98;
-webkit-opacity: 0.98;
}
The first 3 lines are for the background image, and the last 3 for the opacity.

Thank you for a great plugin !