auth-radius accounting is not supported i believe in 6.0 release, it based on src-ip address of an authenticated user for a certain period of time. But if this user is behind a PAT router then all other users behind this PAT router have access if one user authenticated. Furthermore there is no track data being transmitted on a policy unless the COUNT knob was set. There is a limited amount of rules which can count and then data is only counted for all sessions and users permitted by this rule.
i hope this will answer of your question.