Nope, can't rent an extra point directly from MS.
I would go ahead and borrow that extra point from next year. You can borrow as many times as we need (if you have the points), but once borrowed (or banked) they can not be returned to their original years.
You can also bank multiple times within the banking deadlines restrictions.
I think you were thinking of the transfering IN or OUT rules. I believe that this rule has changed to unlimited in OR out in a year but only iin ONE direction.