Richard M. Stallman wrote:

>    It does not work for C-h ?. Maybe that is the only important case though.
>
>That is handled by very special code.  Would you like to implement
>C-M-v in it?
>  
>
Attached is a patch for help.el and help-macro.el (from lisp directory). 
I tried to honor all current bindings to scroll-other-window(-down) and 
also added <prior>/<next>.

I have called <prior>/<next> for Page Up/Down which I think most new 
users will recognize.