Thanks for your reply CrossRoads.
-What is the main differences, or differences between the Nick Gammon's Bootloader and the one that is found in the Arduino IDE?
- I have an Arduino MEGA2560 instead of UNO, I have seen that the bootleader that comes in the IDE can work with MEGA as ISP, but does the Nick Gammon's bootloader work with it too? (excuse me for the dumb question)
-Can this be done (the Nick Gammon method), but using directly an AVRISP MKII instead of using the arduino as ISP?