It requires an ActiveX control. There was once something called reaKtivate, which let you run ActiveX controls in Konqueror. However, I believe it's bitrotted.
You aren't the first person I've seen ask about this. I dunno why they are so popular, they seem to just be like IRC except proprietary. I suppose if your friends are all on there....... well, try chatting to the Gaim developers. They are normally up for supporting a new protocol. I don't think it'd be hard, I can't see it being very complicated.