Drain Oil, remove crossover pipe and oil pan. Depending on you car, you may or may not need to lift one side of the engine to get the pan off. Some guys have used their engine tie down to rock the engine over to one side. If you do need to jack up the engine use a block of wood (piece of 2x4) between the engine and the jack. Locate the jack at the front of the transmission pan. The three bolts at the front of the pan are smaller (10mm) than all the others. There is one bolt on the passenger side that secures a clamp that holds the tranny lines. This one can be a real pain to get off (try using an open end wrench.) There is a baffle in the oil pan and it can hang up on the oil pickup screen. If you have trouble removing the pan, try rotating the engine to get the counterweights out of the way. Removal of the converter dust shield may also provide more clearance. As a last resort, removing the pickup tube guarantees that the pan will come off.
Also might be a good idea to replace the rear main seals since the pan is off.