Ok, I'm not sure about this. Maybe it needs to be worded a little different for me to understand. When we do walking meditation use your awareness to focus on the walking. Not to start thinking of what might come next. If something comes, yes, we are going to note what distracts us. If it distracts us, if the hindrance distract us, then yes, we could think of what Parami we might bring forth to let go of that hindrance. If we are actually fine in the walking and then if we fall into sloth and torpor, one of the techniques Rosemary mentions for the walking meditation, which you may or may not remember, but if you are feeling sloth in the walking, a technique is to walk quicker. Get the energy flowing. So perhaps in the walking, you find you have fallen into sloth and torpor, you can think, "Oh, what Parami can I use, what can I develop here in order to get going?" Here we go, Energy. It is a Parami and a technique that we teach.
But I'm not too sure about using part of the awareness to be thinking of what hindrance could come, because then you are out of what we are teaching here - to actually be aware of what we are doing. Certainly when a hindrance does come, to consider a Parami as an antidote, that is quite ok. What we have done in our general retreat when we teach the Five Reflections, we explain to everyone that now when you are doing, say the walking, you have a hindrance, you can't let go easily, you use a reflection to help let go of a hindrance that is fine. You can also develop Compassion/Lovingkindness to let go of the hindrance, that is fine, and now you can also use the Paramis, consider what Parami to develop to help let go of the hindrance, and that is fine.