Flashing ATmega8 based BL-ESC
Flashing firmware with ISP programmer and enable bootloader
You can enable the bootloader and flash latest firmware in one run. Therefore you need a ISP programmer, ArduinoUSBLinker, Afro USB Programming Tool or Turnigy USB Linker can not enable the bootloader (can not change fuses). Select your programmer and “atmega 8-based brushless ESC + enable Boot loader” and proceed as always. (!!!select correct firmware)
Wait till verification is successfully done and “avrdude done. Thank you.”
Flashing firmware with ArduinoUSBLinker or Turnigy USB Linker
You can now select the ArduinoUSBLinker or the Turnigy USB Linker to update the firmware of ESCs that run simonk firmware 01062012 or newer with enabled bootloader. Nice thing is that you don't have to set the baud rate, compared to STK500V2 programmer that also can be used. But then you have to disable the checkbox and enter 9600 to the baudrate field. See the screenshot for settings (don't forget to adapt the selected firmware).
First connect ESC to the Linker, then plug the Linker to your PC and power the ESC by its power plug. If you run in problems flashing the ESC, e.g. open_ser() not possible or Linker disappears in device manager or gets unknown, try again with the red cable from the servo plug removed.