The native libs don’t actually belong there anymore from what I can tell (or at least they didn’t work for me when I put them there!).
You can put the jars there if you like (of course, you can put them where ever you like as long as the dir is in your java.library.path) but the native libs now have to go here:
(please excuse this, its from memory and my mac is at home)
/System/Library/Frameworks/Java.VM.Framework/Versions/1.4.2/bin
OK - if that isn’t correct, let me know and I’ll get the correct path when I get home. I actually just figured this out last night. I think some of the confusion is that natives used to go in ’ /Library/Java/Extensions’ but now that directory is only good for jar files. Certainly on my 10.3.6 machine with 1.4.2 I have to put them in the Framework path. I swear I tried every other possible place before trying that 
Let me know if you run into problems - I have it all nicely set up in Eclipse in OS X at home, so I should be able to help you out.