If you trash the RedBoot loader during a flashing experience you will not have any method of recovering your Livebox unless you have installed a JTAG connector and built the JTAG cable/adapter. I would install this version of RedBoot as it allows you to break into the boot process by pressing Ctrl-C. Later versions removed the ability to break into the boot process.
Once you have recovered a copy of RedBoot you will probably need a serial port cable in order to use RedBoot to flash a new firmware to the Livebox. You can also use this to change the installed CRAMFS/SQSHFS filesystem images without having to boot the Livebox first.