Multi-threaded console apps

What's the best way to do something like an IRC client where there's messages coming from the network you'll want to display without interrupting the user's input.

I'm using a toy language (MzScheme), so I don't have easy access to some curses library or ptys or anything like that...

Any ideas, or should I just give up and write a curses wrapper?  Can GNU Readline do anything like this?

you don't have to multithread an irc client, everything sent from the irc-server is line for line, even stuff in other channels, you just put it in the correct channel buffer by looking at which channel it belongs to PRIVMSG #channel