<a href="irc://server/channelname" target="_blank">irc://server/channelname</a>
eg
<a href="irc://irc.dal.net/chat" target="_blank">irc://irc.dal.net/chat</a>
no # in the channel name
add ?key on the end if the room is keyd, eg
<a href="irc://irc.dal.net/privateroom?keyhere" target="_blank">irc://irc.dal.net/privateroom?keyhere</a>
