Some people might be not able to flash boot.img file using flashtool or using adb(Like me
showing error root required even i have rooted and unlocked bootloader wiht cwm installed)
So, i searched for new methods but none worked.Atlast I found one THIs one
1. Copy/move your.img file to internal sd of your phone.
2. Download and run the Terminal Emulator
3. Now, type the following commands-
after $ type
su (press enter) (terminal'll ask for superuser permission, grant it)
you'll see this
now type after #
dd (single space here) if=/sdcard/YOUR.img (single space here) of=/dev/block/mmcblk0p9
you'll see 'some records in some records out etc etc'
Press Home key and reboot your phone and its done