I am aware of set_view(); and know that this native can make 3rd person view but with a lot of 'lag'.
There is a way to get into 3rd person view when starting the game up too. If you create a shortcut icon to the mod you play and enter in the target line...
+map mapname +cam_idealyaw 0 +cam_idealdist 90
Then when you start the mod with that shortcut icon and type "thirdperson" in the console it will put you in 3rd person view. Once you exit that map though, and try to go to a different one the thirdperson command will no longer work.
Is there a possible way to make a plugin that would enable clients to be able to use the "thirdperson" command?