Content Lock CPA Script

I would to create an ajax script like the one at http://imagebam.com. For example if you go to [login to view URL] you will see the script warning you and asks you to enter. I would like something similar to that and willing to pay $10-20 for it. I will need it to be aviable in one .js file that I can easily install into my site . I would like to be able to customize the cookie duration, meaning how often (every 3 hours but I want the ability to change it easily in the future) I want the script to appear over a duration of 24 hours. Also instead of the "Enter" text, I would like it to be a picture (Jpeg file, size 300 x 250) of "Enter" instead. I can create the picture myself, but I would like to know where in the code to insert it. So therefore, they must click on the picture to be able to enter and nothing else. If you have any more questions, please let me know.