sure, i'm natural and have done it. the key to success is to eat lots, sleep lots, have a good diet strategy, keep all other stresses to a minumum. it is freaky volume, but you only use about 60% of 1RM. that said overtraining is a concern for those with busy schedules. i wake up and sit in lectures all morning so my stress level is very low, the only activity i do when on such a program is the workouts themselves. this is no time for cardio. however, many naturals find they can make similar gains with as little as 5 sets per body part, so why bother doing 10 and then accesory exercise.
i will post a diet routine and suggestions for naturals who want to do GVT.