Display username as image

[nosaes]

Hello,

I'm trying to figure out how to display certain members of my forum's usernames as images, similar to staff members of this site. I read about a way to do this using replacement variables however that method replaces every instance of the user's name. I only want it to be replaced in the postbit and on their profile.

Is anyone aware of a plugin, hack, or method to go about doing this? Searching Google hasn't proven very helpful for me.

Regards.