I very much doubt you'll be able to find just the kernel anywhere. AndroidFirmwares.net may have it (I can't check as it seems to be down for me at the moment), but don't count on it. Best thing you can do is get the entire rom from Samfirmware & flash that.
And before you ask, no, this will not wipe your phone. I can't think of a logical reason why you'd want to use this kernel with anything else, so that's what you're going to need to do if you want that kernel.
Edit - AndroidFirmwares is up, they don't have XWKK5; closest they have is XWKK2.
Extra edit - If you can find the rom concerned but really really really want to just flash the kernel, do the following (this may or may not work though):-
1) Download the entire rom
2) Use 7Zip/IZarc/similar to extract the zImage (kernel) from the .tar.md5, put it aside somewhere
3) Download any kernel from AndroidFirmwares.net
4) Extract the tar.md5 from the 7Zip archive you download
5) Open the tar.md5 with 7Zip & you'll see there's only one file inside, the zImage. Take the zImage (kernel) you extracted from the stock rom in step 2 (I.E the kernel you want to flash), and swap it into the tar.md5 of the kernel package you downloaded from AndroidFirmwares
6) Flash with Odin as per usual
Now...If this doesn't work, it's going to fail at step 5 - you may not be able to swap the zImage of the kernel you want to flash into the kernel package you downloaded from AndroidFirmwares, you may end up with all kinds of errors. I'm not going to be around to troubleshoot this for you if you go down this path, because the alternative (flashing the entire rom to get the same result) is infinitely simpler - you're on your own if you try this & have problems.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Failure to search is the leading cause of male impotence on XDA
If you don't know how to recover if things go wrong, what are you doing flashing custom roms ?