Coil pack is where plug wires originate, what you are calling distributor cap. Distributor function on our cars handled by PCM (Powertrain Control Module) located behind glovebox.
Procedure outlined is to get access and visibility to get an O2 sensor socket on sensor, not your arm.
Haven't done myself yet, so I'm only relaying info and providing interpretation, however I have replaced EGR tube beside sensor so I'm familiar with area. While sensor clearly visible from below car, problem is getting room to swing an open end wrench; however, here's a thread that uses a stubby:
http://www.contour.org/cgi-ubb/ultimatebb.cgi?ubb=get_topic&f=3&t=003805&p=
