By default, the chat rooms that XOs create with Sugar are not searchable. Meaning that when you list available chat rooms in a regular client, you won’t see them and thus can’t join them.
You can use Psi or Pidgin to configure the XO Chat room so everyone can see it and join it.
Psi
In the Psi buddy list window, go to General -> Service Discovery
Expand the Chatrooms list. If there’s a Sugar chat, you’ll see it listed as a bunch of letters and numbers. Right click on it and select Join. You’ll be placed in the chat with the XOs.
We still need to configure the room so everyone can see it. In the upper right of the chatroom, you’ll see a button that looks like a couple of down arrows. Click that and select “Configure Room.”
Under the General tab, click the tick box next to “Make room public searchable.” Click Apply, then Close.
Now the XO chat room is visible so everyone can select it from the chat room list like a “regular” chatroom and join it.
Pidgin
Go to Tools -> Plugins
Click the tick box next to XMPP Service Discovery.
Now you can go to Tools -> XMPP Service Discovery -> XMPP Service Discovery
Make sure the account and server you want is listed in the Account box. Click Browse and Find Services.
Expand the Chatrooms item. It should start with the word “conference.” You’ll see the Sugar chat listed by a bunch of letters and numbers. Right click on it and Add to Buddy List. Click Add. Close the Service Discovery window.
In your Buddy List, right click on the Sugar chat you just added and select Join. The chat room window will open and place you in the chat with the other XOs.
In the message window, type /configure and hit enter. A box very similar to the Psi chat room configuration box will pop up. Click the tick box next to “Make room public searchable.” Click OK. Now everyone can see the room in the chat room list.