Originally Posted by SterneSchreien
How can I flash clockwork mod recovery? And if in the end it does not work with my phone will it become bricked?
You will most likely trip the flash counter when you install the custom recovery, it may matter to you. If it does you can use the Triangle Away tool to reset. [Howto] Install a Recovery
discusses manually, using either adb or terminal emulator, installing a recovery and links to other threads with automated installations. The most recent CWM for the SGS3 is 188.8.131.52 you can get it from http://www.clockworkmod.com/rommanager
Using the manual method you can install recovery without using Odin or Heimdall.
Since you are rooted, GooManager would work for you. A number of people with Canadian versions of the SGS3 have reported that they used GooManager to flash the d2att version of CWM with complete success.
To install with Odin or Heimdall you will need a version of the recovery packaged as a .tar.md5 or .tar. Be sure to get the most recent version of CWM. It can be found with a search of the forums. There are tutorials available about using Odin, in short put the .tar.md5 into the PDA slot. Bear in mind that I don't use Odin, read about it for before using. Caveat, some older ROMs may require an older version of the recovery.
(I edited my previous post to correct a misstatement on my part, I changed bootloader to recovery)
TW 4.1.2, stock, rooted,
Samsung Captivate SGH-i897
Currently CyanogenMod 10.1.3
resurrected from softbrick using 4-2ndtwin's Heimdall OneClick to stock Gingerbread - 2.3.5 - kk4
ROM history Eclair > Froyo > Gingerbread > CM9