CentOS/Redhat 6 support installing and booting using GPT partitions, which can be larger than 2 TB. Your BIOS must also support UEFI booting. For a new install on an unpartitioned drive, wait for Anaconda (the graphical installer) to start, then press ctrl+alt+F2 to get a shell prompt. Create a new partition table on the blank drive:
parted /dev/sda
> mklabel gpt
> quit
Press ctrl+alt+F6 to return to the installer, Anaconda should recognize the drive at its full size and let you partition as normal. Make sure you don't choose the option to wipe the entire drive, or you'll get an old DOS partition table. That's it!