Nothing is impossible, and the ABS system is just a control module, two ABS pumps and two wheel speed sensors and tone wheels plus wiring and hoses. The trick will be integrating those onto a bike that was never designed for it. The tone wheels are probably straightforward, and the speed sensor is integrated into the right front calliper mount on a 6th gen, maybe that is interchangable with the calliper bracket on a 5th gen? And the rear sensor mounts on the brake bracket which also might be interchangeable? There's a lot of empty space on the left front subframe of a 6th gen where the ABS module lives and space elsewhere for the pumps. Not sure if the same is true on a 5th gen.
nearly impo$$ible, not worth the agro, forget it. in theory, if you practice hard braking skills often, u could do almost as well as ABS. great if u could do it cuz ridin in rain and braking may scare some riders. do moto GP or WSB riders have ABS ?