You might take a look at this page on Apple Support. I'm not sure if it is what you need, but it is worth a look.
http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh1777.html
"Solving problems with keychains
If you have some experience administering computers, you may be able to identify and resolve some keychain problems by using Keychain First Aid.
With Keychain First Aid, you can:
Verify and repair keychain settings and permissions
Reset a keychain (delete a keychain reference while preserving the keychain file)
Make the login keychain password the same as the login password
Set the login keychain as the default keychain
Set the login keychain to always remain unlocked"