See the spark plug DIY threads, it explains how to remove some of the coils if they are in a tight space. I didnt pay attention and actually broke one of them while forcing it into the hole. It was much easier after I followed the thread.
Im not sure, but I think you can run the engine and disconnect each plug by unplugging the coils one at a time. The one that doesnt affect the engine is the broken one usually. Alternatively connect to an OBD reader and google the code for the cylinder number.