I'm not entirely sure since I haven't done Doll myself, but I know one girl who did the headdress by making a paper mache mold of her head (plaster mold first, then the paper) and attached the rosses to that. She's put quite a bit of information on how she did the whole costume here: http://clamwings.deviantart.com/art/...rcus-144171355
Another way you could go about the headdress is to do something similar to lace-wig making except maybe using something stronger than wig-lace for the base so it won't tear. This is a fairly short tutorial on how to make lace-wigs, and the way they get the client's scalp mold is quite handy if you don't want to do the plaster method: http://www.youtube.com/watch?v=QK8F3FkE8YA
Cheers and good luck!