Stuff as many rags as possible down around that fitting with the phillips head screw on the top,cram them down underneath too if you can that will catch as much oil as anything.Remove the phillips head screw and let the oil flow out until there are no more air bubbles,put the screw back in without dropping it down into the bellypan hopefully.If your still a little concerned about air you can always yank the oil pump cable wide open once the engine is running and hold it that way for 10 or 20 seconds,that should really make sure there's no more air in the line.