[SmartcardServices-Users] Smart Card Login in OS X 10.6.8

I am having trouble enabling smart card login for local users in OS X 10.6.8.  I have been able to enable this feature in the past, but now the login window just blinks when I insert my token and I am not prompted for my PIN.   I believe my authorization file is correct based on Apple's article for enabling smart card login (http://support.apple.com/kb/TA24244).  Specifically, I am using sc_auth to add my certificate's public key hash to the local user's directory record as described in the article.   Has support for smart card login been removed from OS X 10.6 as well?   Thank you in advance for any help you can provide.