yes you were able to use it becuase you were having a custom rom becuase some cooks enable it by tweaking it out in the registry.... but as far in your diamond you can't used it cuz sprint disable that feature and pay close to 40 bucks for that (correct me if i'm wrong)...
but you can download the cab here.
http://forum.ppcgeeks.com/showthread.php?t=37947
hope it help