http://forum.forumer.com/showthread.php?t=5397 
Basically, what it's saying is to upload your desired user groups into your forum database by treating them like emoticons (just don't set them as postable smilies), then put in the user group command what the link has (I forgot what it was exactly).
Skip the purple legend completely (it'll jack it up; darn you,
Ali!

) and continue with the image at the end.