As yet there have been no changes to the system.
You get the form from the garda station or from the RSA website. What happens in the Garda station is that "you" are declaring to the motor tax office by way of signing the form that the car has been/is off the road. The Garda mearly witnesses this declaration.
He/She may ask you some questions, or may not. They can decline to wittness the form for whatever reason or they may ask you for some proof, or not. They most likely will if you are declaring it for a long period retropectively.