In the "Post Icons" section of the Administrator control panel, you can setup new post icons. I copied and pasted the addresses of the smileys and removed the leading part of the address to make it relative.
For example:
http://www.allofftopic.com/images/smilies/naughty.gif became images/smilies/naughty.gif
I did that because the existing post icons were relative links, it's probably not necessary.