How to install custom firmware on Samsung Galaxy S III with ClockworkMod Recovery (CWM)? Yeah… We don’t want to stay on stock official firmware all the while, right? Try out the latest and greatest custom firmware which loaded with newest stuffs and better tweaks and hacks. And lots of fine tuned custom Android ROM are available for Samsung Galaxy S3. But before install a new custom firmware with CWM, be sure to make a full system backup with CWM first. Because the new firmware will replace your existing firmware.