I guess one could do it if one wanted to badly enough. The Gen II has radially mounted front brakes and the wheel is different, so essentially you would need a complete Gen II front end. The rear brake and swing arm are different and use a different wheel, so the entire rear end would need to be upgraded to Gen II as well. Would likely be better and more cost effective to just buy a gen II with ABS already on it. It would be a fun project though.
if its just the ABS you want you don't need to change the brakes themselves..............however you would need to get brackets to mount the wheel sensors front and rear as well as get the wheels or sensor rings to suit.
The ABS system you need all the main parts...ABS ecu,pump,sensors and any control valves plus a whole heap of brake lines.