The V2 and Scud are basically used in the same way as Artillery/Off-Board Artillery (see Rulebook page 10).
For the scenario Endsieg this means that you place a V2 counter in hex BB4 and BB5 for the Reich, representing immobile V2 launch sites.
The Nato deploy their Scuds anywhere adjacent to Geseke, representing mobile launch sites.
The Black Hand deploy the Scud in hex O19 and the V2 in hex P19.
When a faction activates, the V2/Scud can be used to attack a hex in LOS or the CO/2IC/Recon Units can be used to call in the strikes against any hex in their LOS.
Every unit in the target hex and all 6 adjacent hexes are attacked with the appropriate firepower (14AP and 8HE).
After use, remove the corresponding V2/Scud counters.
In certain scenarios, see Scenario 10, Cassino Redux, you can choose the Warhead for the V2/Scud (Barrage, Chemical or Smoke).
Baal's balls, I totally missed that. Thanks Christian!