Also, you should probably not be querying sys.dm_exec_sessions, sys.dm_exec_requests, or sys.sysprocesses directly becuase you probably won't have the correct permissions.
Maybe that's why I never got it to work properly, but at the time it seemed to be trouble with nested stored procedures where the wrong value persisted during execution of child procedures. It might be easier to roll your own by creating a permissions table and using triggers and OBJECT_NAME( @@PROCID ) to validate that the data manipulation is happening according to your rules.