Aside from the two you asked for, there were two others that I thought might be recognizable and simple enough to put together...what do you have to work with? And I apologize if anything is confusing...
Death outfit: (crappy screenshots are crappy) Full (http://lostlink.files.wordpress.com/2008/07/code-geass-r2-13-shirley-lying-in-a-pool-of-blood.jpg) Top (http://lostlink.files.wordpress.com/2008/07/code-geass-r2-13-shirleys-confession.jpg) The skirt has a triangular notch (http://moe.imouto.org/post/show/72723/code_geass-nanakusa-shirley_fenette) in the center back hem, about one and a half inches high. You could easily take a longer pencil skirt and attack it so that the length and hem are correct. The blue and white parts on the shirt look like they're holding pockets closed; to make them sew the blue buckle part to the bottom edge of the white strip representing the pocket. Sew that side to the shirt so it looks like the blue strip is coming from behind and folding over. Then sew a smaller white strip about an inch (or less) below that so you can thread the blue strip through.
Maroon top outfit: Fanart (http://i46.tinypic.com/2d0djqg.jpg)
Green dress: Full (http://safebooru.org/index.php?page=post&s=view&id=20623) Ridiculously high res for the necklace (http://gelbooru.com/index.php?page=post&s=view&id=428666)
Mutuality dress: Full (http://gelbooru.com/index.php?page=post&s=view&id=430823)
I think the Mutuality dress would be the easiest and most recognizable one that you could put together unless you have a top similar to Shirley's death outfit lying around. The bodice wouldn't need to be exact; you'd just need to attack a similar (sleeveless and empire-waist) white dress with pink ribbon and lace. Angel wings optional. I'd check thrift stores for outfit pieces since yours might show up and you've probably spent a lot of money on this cosplay already.
And if I may ask, where did you buy the original outfit? It may not have been shipped until very recently because of Chinese New Year if you ordered it from eBay; not all sellers post that they're on vacation.
(no subject)
Death outfit: (crappy screenshots are crappy)
Full (http://lostlink.files.wordpress.com/2008/07/code-geass-r2-13-shirley-lying-in-a-pool-of-blood.jpg)
Top (http://lostlink.files.wordpress.com/2008/07/code-geass-r2-13-shirleys-confession.jpg)
The skirt has a triangular notch (http://moe.imouto.org/post/show/72723/code_geass-nanakusa-shirley_fenette) in the center back hem, about one and a half inches high. You could easily take a longer pencil skirt and attack it so that the length and hem are correct. The blue and white parts on the shirt look like they're holding pockets closed; to make them sew the blue buckle part to the bottom edge of the white strip representing the pocket. Sew that side to the shirt so it looks like the blue strip is coming from behind and folding over. Then sew a smaller white strip about an inch (or less) below that so you can thread the blue strip through.
Maroon top outfit:
Fanart (http://i46.tinypic.com/2d0djqg.jpg)
Green dress:
Full (http://safebooru.org/index.php?page=post&s=view&id=20623)
Ridiculously high res for the necklace (http://gelbooru.com/index.php?page=post&s=view&id=428666)
Mutuality dress:
Full (http://gelbooru.com/index.php?page=post&s=view&id=430823)
I think the Mutuality dress would be the easiest and most recognizable one that you could put together unless you have a top similar to Shirley's death outfit lying around. The bodice wouldn't need to be exact; you'd just need to attack a similar (sleeveless and empire-waist) white dress with pink ribbon and lace. Angel wings optional. I'd check thrift stores for outfit pieces since yours might show up and you've probably spent a lot of money on this cosplay already.
And if I may ask, where did you buy the original outfit? It may not have been shipped until very recently because of Chinese New Year if you ordered it from eBay; not all sellers post that they're on vacation.