You install in on a laptop as a server you can use
Xammp to make the setup easier. It contains SQl and PHP so you should have your server up and running after a few minutes. Then you copy the files to the htdocs folder then use the
http://localhost to access the chat. Just remember to use the phpadmin feature of Xammp to create a database call ajax_chat then inport sql file from the folder. After doing this you should be able to log in. As for any clients who wish to connect you will need to give them you Ip address and they will input it in their address bar ie
http://192.168.1.1 they do not need to install anything. You may want to install it on a server that is not a laptop and assign it a static ip so when you reconnect to the wireless you will not have to check for a new IP and give that info to anyone who wishes to connect.