Eggs can be obtained by collecting a live mated female and placing her in a small (12" x 12" x 12") popup cage and then, lastly , placing the cage over host plant as shown in this picture.  This is an anise swallowtail (Papilio zelicaon) female; but, the principle is the same.  This setup will work with eastern black swallowtails (Papilio polyxenes asterius) as well.