Update a custom GpuProgramParameters constant which is derived from information only this Renderable knows.
This method allows a Renderable to map in a custom GPU program parameter based on it's own data. This is represented by a GPU auto parameter of AutoConstantType.Custom, and to allow there to be more than one of these per Renderable, the 'data' field on the auto parameter will identify which parameter is being updated. The implementation of this method must identify the parameter being updated, and call a 'SetConstant' method on the passed in GpuProgramParameters object, using the details provided in the incoming auto constant setting to identify the index at which to set the parameter.