This is a step by step how to on how to install xchat. I take no responsibility for anything that might or might not go wrong.

Step 1: Open Terminal
Step 2: Type in this command: sudo apt-get install xchat
Step 3: When it asks you if you want to continue type in y
Step 4: Now xchat will install.
Step 5: to run xchat, go to Applications>Internet>XChat IRC.

There you have it.