Solved - thank heavens for Google!!
if (document1.getAttachmentList("Body").isEmpty()){
attachmentNames = "No Files Yet";
} else {
var v = document1.getAttachmentList("Body");
for (i=0; i < v.length; i++){
var eo:NotesEmbeddedObject = v.get(i);
attachmentNames = attachmentNames + eo.getName();
var att1:NotesEmbeddedObject = courseDoc.getAttachment(eo.getName());
att1.extractFile("D:\\temp\\" + eo.getName()); <============= Dumb blindness prevented me from seeing the obvious
sessionScope.put("att"+i,eo.getName());
}
}