Why would this be required?
Like how the official implementation currently works with Vehicles there is the driver (Client), the Authorative (Server) and all other players (Remote). The aim for this would be so mods such as Expansion or HypeTrain can take advantage and offer a smooth gameplay for the drivers of the vehicles they are implementing.
Currently there is no way to make a client prediction system for helicopters since the server will authoritate quickly on the actual position of the helicopter thus jerking the driver back making for an uneasy ride. The only way we have found in Expansion to stop this is by only using the server position and having no client prediction on the logic. This will lead to bad situtations with a reasonable but high ping of above 5ms and less than 100ms and having a way to stop the synchronization of the position for a particular client would be great.
How ever it is currently done for the Cars should be exposed to script.