I've delt with Fedora's lack of mp3 support a couple times, but now I have a different problem. I want to play mp3s on a workstation at school on which I do not have root access.

The easiest thing I can think of would be to download an executable for a music player that has mp3 support, but of course, we're dealing with Linux, and nobody ever makes life that easy. So is there any kind of plugin for one of the existing players that I can install without being root, or any kind of software that doesn't require root to install?

Most of the software don't require a root to install (sometimes a wizard is needed, though).

I would start from mpg123 or mpg321.