Not to be a doubting Thomas but I don't think using a tablet with Poser weight painting will make much of a difference. I have one (and also use an HP tablet convertible laptop) and find it only useful for drawing type tasks. With weight painting it's not drawing that needs a significant amount of fine "gesture" or pressure variation as in weighted line work you might find by utilizing a brush. If you're not used to using a stylus and tablet it might actually make things more cumbersome as you don't have the by rote muscle memory of selection and such with a mouse.

Just a caveat, some people hardly use a mouse at all because they're very used to a stylus