There is no specific height or age requirement for lift loading, but as per the responsibility code, prior to using any lift, you must have the knowledge and ability to load, ride and unload safely. This includes the carpets.
The GoldRunner Coaster riding requirements: Drivers must be 54in tall, Riders must be 38in tall. Riders may ride along with a driver that is at least 16 years old and a head taller.