I didn't know that TViX boxes supported HFS or HFS+. The manual, in the Specifications section, lists "NTFS, FAT32" in the File Formats section with no mention of HFS or HFS+. I suspect that you are having problems because HFS isn't actually supported.
OS X doesn't have a way to wipe a disk - you can reformat it, but that installs at least one partition. You can not delete the last partition on a disk using the GUI.
One thing to try - FAT32 can actually support disks over 1TB, but Windows won't let you do this. Try mounting your TViX on your Mac and formatting the disk again. Use Disk Utility, select the TViX hard drive, and in the "Erase" tab set the Volume Format to "MS-DOS File System" which is actually FAT32. (Do not pick the FAT16 version, which has (FAT16) appended to it.) I don't know if it will let you, but try formatting the entire disk that way, and see if the TViX will recognize it.
If it doesn't, I can think of three options:
1) Create four FAT32 partitions, as big as the system will let you. This is ugly because it chops up your drive, and FAT32 has a file size limit of 4GB.
2) Install Parallels Desktop on your Mac, and then install a version of Windows as a guest OS. This allows you to run Windows on your Mac, and then access the TViX from the guest version of Windows. Its a good solution, as you can then use Windows to format an NTFS disk and to write to an NTFS file system, but it involves buying a copy of Parallels and Windows. I'm not a windows expert, but I imagine the cheapest edition of Windows XP support NTFS. (If you don't mind dual-booting you can use Apple's free BootCamp instead of Parallels. Then to get to Windows you have to reboot your Mac into Windows instead of running under OS X.)
3) There are some experimental add ons to OS X that give it the ability to write to NTFS file systems, but they are not for the timid. See How to read and write ntfs partitions on Mac OS X
for more info.
Another option is to take the TVIX to a friend with a PC and use his machine to format the drive back to NTFS. They you will have to use the TViX's built in FTP server to transfer files via the network, which will be on the slow side.
Hopefully you will be able to use one big FAT32 partition. If not, I'd vote for 2) if the wallet allows it. Being able to run Windows on your Mac has other advantages.