different user icons for different chatter?

[phpchat]

I have a member's table, where if users are already logged on the site, they need not log in again to chat ($params["nick"] = $_SESSION["username"];)

Now, before they go to chat (assuming they're already logged in), I would like for them to select different chat icons that will be displayed next to their screenname. At this point, there's only "default/images/user-me.gif" but I would like to add my own icons "userred.gif", "userblue.gif", "usergreen.gif", "userbrown.gif" and so on.

How would I do that?

[phpfreechat]

Currently it's easy to do that.
I will implement user's metadata in future so wait for that and it will be fesable.

[phpchat]

For the time being, since I would like implement it now, do you know what files I should modified?