You probably have your hair all figured out, but here's my two cents.
I'm horrible at hair, so last year when I decided to be the Bride I had a panic attack when I couldn't find any help on the internet on how to do my hair. My only attempt before the event was a huge failure. I had stuffed some kneesocks with newspaper to attach to my head and then brush my hair all around it to give it some height, but I couldn't get the sock to stay, so I eventually gave up, defeated.
The night of the event I decided that I didn't care as much about height, as just getting the idea across. I ended up making little buns kinda like this(kinda):
all over my head (this is not me in the picture by the way,) You know, the fast little buns where you almost make a ponytail but don't pull it through all the way?
I made those buns on the back of my head and let them build up on eachother for some height and I left the surrounding hair out of the buns so I could tease it and pull it back to cover up the buns. I then added my white hair pieces and voila! Kinda half-assed Bride of Frankenstein.
You can see my pic in my album here:
Halloween Forum - HappyScientist's Album: Halloween Costumes 2007 - Picture
So that's how I did it. It got the look across and people knew who I was. In fact, someone told me I was the sexiest dead person they've ever seen. (They had been drinking quite a pit however. Ha ha!)