Not many of us have the privilege to do so. For me whenever I do get to snowboard in glacier terrain the riding actually becomes secondary. One must have a harness and a locking carabiner on. When walking on glacier terrain use your probe to ensure that your very next step finds solid ground. To go an even safer route is that you use a rope, tying that to your harness betwen your guide or your partner and keep the rope taut when walking with a distance betwen each one. Another way could be to bury an anker such as your snowboard with a rope about 1,5m deep. Protect the rope from your edges with a glove for example. Once got to the point of strapping in make sure you keep the speed and avoid any sink holes. And now Why would anyone ride in such risky enviroment? Probably because at the end it is an interesting fact of how this seemingly unridable terrain gets a small stage of progression - when every step is thought about and everyone in the group makes the effort to eliminate risk it still can become a zone of comfort. Probably just the same as riding urban terrain.