This doesn't answer your question but I thought you might find it interesting:
costumersguide/Sweeney Todd/sweeney - Photobucket - Video and Image Hosting
someone is doing a study of the costume and posted a buch of great pics. It wasn't youwas it?
Also a little video I found at:
How To Make Sweeney Todd Victorian trash costumes | Wonder How To
On a you tube video the costumer for the movie said she just had an old neckerchief and that is what they used.