Here is the code for the simple AJAX online collaboration document store I wrote a while back.
You should just be able to upload it to the document root, edit the header.php and footer.php files to your design and everything should work. If not, try editing it to get it working on your server.
I'm a web developer based in the East Midlands, UK and if I keep up the current rate, I might have developed 3 million sites by the time I retire