I've used USB sticks and a disk but no menu item for formatting the disk appears. When I connect the disk, the contens appear in the screen but no formatting can be done. I have T-MST14DEUC-2900.0 firmware on the box.
Are you sure the TV supports live recording? Try inserting the USB drive, go to the channel list and select a program, hit select and see if a record option pops up. I couldn't find much information on that model.