You can add a link to this page
http://webchat.quakenet.org/
and customise the link to provide a default channel like this
http://webchat.quakenet.org/?channels=a ... ime&uio=d4
Which will prompt the user for a nickname and automatically join
#alteredtime.
You can also customise the colours. Check out their wizard by going to the first link, and up the top left click the dropdown then
Add webchat to your site. Then just include it on the site in an iframe, or a popup window or whatever you decide.
This saves you worrying about hosting one yourself. If you really want though you can host it yourself and set it up but there really isn't a need.