the device i used is my phone, Galaxy Nexus. i started with something like 4.1.1, but that doesn't really matter. in this post, i am trying to note down only certain keywords. those who know about them may find it useful, as you might not be able to recite some operations. those who haven't known about them, can Google them as well.
adb reboot bootloader
adb reboot recovery
fastboot oem unlock
fastboot oem lock
fastboot flash recovery CWM-6-blah.img
fastboot update -w takju-blah.zip
fastboot update takju-blah.zip