I think there's something that's part of XFCE4 I used EXACTLY for this. It's somewhat easy to use, and has a GUI
It's got something to do with Thunar, I'm pretty sure. Anyway, it should be part of the CentOS XFCE package, I'll try to figure it out. If you don't mind downloading a whole new desktop environment, (:P Sorry) that might well be the way to go. In the meantime, I'll try to figure out what the name is so you can install just the renamer.