The icon is not sent as an icon, it's sent as a text smiley as usual: a column followed by a closing parenthesis. This text is interpreted by the IRC client and displayed as a graphical icon.
Some other IRC clients do that, MSN does that too.
This would be a feature wich you can disable so that the smiley appears as a text smiley, or enable so that the smiley appears as a graphical icon. In any case, you would type it as usual (text) and it would be translatted upon receiving.
