typically in poser you have the pose library open , have the figure selected and click the + button to save the pose. You get prompted to save morph settings , and body settings and I think you can save a subset of body parts.

I dont know if P8 does something different.

Mat poses can be done by saving a material collection and then editing it to be a pose file. Thats in these forums lots of times , try a search for mat pose .