If you are WILDing, you need to have every muscle in your body relaxed. That is one of the primary focuses of WILDing, staying relaxed in preparation for sleep. If you are trying this technique, make sure you are performing this impossible movement with your mind. Try to bend your finger or whatever with your mind and not with your actual body. Your actual body shouldn't be doing anthing but relaxing as if it were already in the sleep state. I'm not familiar with this technique, but just going by the information given and my experience, I hope I was able to help out a bit. If you have any further questions, don't hesitate to ask.