I've never heard the quality of those Kontakt drums, but I'm sure you can find them by simply googling around. That's of course if you want them that bad. There's plenty of 808 kits out there though.
Have you tried "Nepheton" VSTi plugin?
d16.pl/index.php?menu=153 <<<Website, copy and paste
It's a very good emulation of a real 808. So that way you can tune the kicks and all such sounds that come with an 808 drum machine. It comes with a built in sequencer like the real one, but you don't have to use it of course, just use the sounds.