http://linux.byexamples.com/archives/318/how-to-trigger-xchat-from-firefox/
When you hitting irc url such as irc://irc.freenode.net/lbe in firefox, is it possible to open up in xchat?
The answer is yes. How?
You need to add two lines of firefox config.
If you are advance firefox user, you must already know that where to add firefox config, that is a hidden feature of firefox which allows you to customize a lots of things. First, type this into url text bar.
about:config
You will be open to firefox config page which list all the firefox configs. Observed that, there is a filter text bar just below your tabs. First lets check to see whether the irc protocol has been implemented.
Insert the line below into filter text bar to check
network.protocol-handler.app.irc
If nothings returns, you need to set it manually, else you are lucky, you can clicks on the irc links, it may probably open xchat for you.
First of all add a boolean config by right click on the page and select New->Boolean
network.protocol-handler.external.irc
Set it to true.
Next, create a string config,
network.protocol-handler.app.irc
And set the string as
/usr/bin/xchat -e --url=%s
Now, its done. No need to restart firefox.
For more info, kinda refers to Gentoo Linux Wiki . You can implement for mailto:// and others protocol as well.