Most of the misses against London were due to British intelligence leaking direct hits as overshoots, thus the Germans corrected for the non-existent overshoots, and the V2s fell short from then on.
Considering that the German program to get HUMINT from the American mainland failed miserably AFAIK, they'll have no way of knowing exactly where their missiles fell.
The Americans will probably do the same thing the British did in real life IIRC; that is reporting on the BBC and such that the German missiles (in IOTL V-1's) fell more to the SW then they really did, resulting in the Germans aiming their missiles more and more in the NE direction of London.
They can't really correct their fire anyways, considering that the launching point will be different everytime, because the Germans don't have anything like LORAN AFAIK. Unless you'd have a submarine firing multiple rockets after one another from the same location, which goes contrary to every SLBM doctrine around.
So the Germans have no way of either knowing exactly where they are aiming
from as where they're aiming
at.
Impossible, the V-2 had a very complex firing procedure that took nearly an hour to set up. It also had to be accurately aligned to face it's target, I saw a film of this process in a documentary that asked just this question, it was pretty clear that trying to carry out this on the pitching deck of a U-Boat would have been totally impossible. There also would have been the ever present danger of being located by aircraft or ASW ships and sunk.
So in short the answer is no way.
As AdA mentioned, it took the Soviets (and the Western Allies) a decade+ to get SLBM halfway accurate. It took them untill 1960+ to get the first underwater launch, which greatly aids the possible submarine's survival.
Unless the Nazi's somehow manage to survive untill 1955, it's a no go.