IRC is too easy exploit and troll, how bout ajax chat?
I don't know about the exploits, but as for trolling, I run my own irc server that gets next to no traffic (therefore no trolls) at the moment and I would be willing to host a channel for this site. Let me know what you think.
As for Irc in a browser, I recommend mibbit. And you don't need to mess with smf. You can use the mibbit iframe code on a new html page and just link to it from wherever you want.