Cont..
If you just want to store in a different document then you can use something like this:
var doc:NotesDocument= currentDocument.getDocument(); // or document1.getDocument();
var item:NotesRichTextItem;
item=doc.getFirstItem("AIF_Attachment");
var doc2:NotesDocument= database.createDocument();
doc2.copyItem(item,"AIF_Attachment");
doc2.save();
Hope this helps..!