Bitknitting has a thorough walkthrough for the FRDM-KL25Z including updating firmware, installing OpenOCD and the mbed SDK.
The goals of this post include:
Installation and verification of OpenOCD with my FRDM-KL25Z board. Setting upEclipse/OpenOCD. Installing the mbed SDK and running test binaries built using the mbed SDK on the FRDM-KL25Z board.