You need to fit them in at least twice a week if you're going to do any real good. Do sets of 2's & 3's in Snatch and 3's in clean. I would not even mess with power cleans, it will only mess up your learning for full cleans down the road. I wouldn't mess with the difference in rep ranges for your program either. Just hit 5-8 sets as part of your warm-up for main exercises like mentioned before, but keep the weight light to work technique.