UT2003 Epic Bonus Pack One for Linux
This is where you can get the UT2003 Epic Bonus Pack One installer for Linux.
The Community Bonus Pack can be found here
The Digital Extremes Bonus Pack can be found here
Here's a shot of the installer:
Download the Epic Bonus Pack One Installer (md5sum).
The installer is approximately 135MB.
Run the installer as the same user you installed UT2003 as.