Intended use of session and HTTP_*_VARS.

While looking at both the session documentation on the site and digging through the comments in the NEWS and ChangeLog files I am a little confused about which way I should implement session. Registering vars from the global scope seems to work fine. However it would seem that any attempt to write data directly to http_state_vars will not work. I reviewed older postings refering to some if not all of the http_*_vars being read only now. I attempted changing track_vars and reg global options in the ini file in order to do away with the global vars method at get to a track vars only method. It would seem that keeping the global scope free of any session vars you would have to be able to access the http_state_vars. (read/write/destroy) Is there something I missed? Any help would be most appreciated. Thanks.