You don't need any changes in the code..so the unofficial patch is not needed (as I know of). It's up to the map makers to make these changes to their maps.
Make however many spawns you need, do the regular map making route. However, name them all the same thing (by room of course, only vary their name by being in a different room).
Edit the func_door_nzp to have something like this...
...where every TargetX (including Target) is listed as your zombie spawn.
In essence this will force the spawn to be reactivated.
This has not been tested for non-linear maps such as Wahnsinn.
Proof: Warehouse is now playable