All this while i thought all the ESCs were using Atmel processor which can be flash using an USBAsp for Atmel. But after stripping his ESCs of its heatshrink and searching through the internet, seems like i was wrong. His ESCs are using SiLabs chip which is use in almost all the new ESCs design. Thus my searching begin.
What i shared here just some information on how i've done it. I might miss something important so please use this just as additional information for your own use. Do some research and fully understand what your are doing before you proceed.