I agree on that one, is it even allowed? Atleast the most companies paying you for having ads don't let you have hidden ads, like the one popping up when clicking the username input, maybe it's time to report this website.
Okay, I didn't check but I guess when you're using full AJAX, you push the URL and have some function to check the URL and load the proper page everytime right?
There are services online, google .htaccess to web.config and a bunch of websites will show up, oooor use URL Rewrite with IIS, however prepare yourself, it might not convert all the rules, in that case you would have to add them yourself.
A friend of mine actually coded this for a hotel, a casino system that worked like that and that ended the game when one got over 21 and such. I can talk to him and see if he is willing to release the code for that unless @JayCustom wants to go at it