use optiloader sketch to load optiboot bootloader. all you need is another uno or mega to load the optiloader sketch, hook up your atmega328 based board whose bootloader you want to update, and run the sketch.
use optiloader sketch to load optiboot bootloader. all you need is another uno or mega to load the optiloader sketch, hook up your atmega328 based board whose bootloader you want to update, and run the sketch.