I have a friend who did Sasuke hair and told me she had someone layer hairspray and take a hairdryer to it quite a few times while she laid with her head hanging over the side of the bed.
I myself, have gotten straight-up gravity-defying Sora hair with a hairdryer and hairspray, in about fifteen to thirty minutes. If you layer it with enough hairspray and product, you CAN sleep on it (someone I know did a good job keeping his Roxas hair all weekend because he put enough crap in it XD).
If you have someone willing to help, it'll go a lot easier. I couldn't get the back of my hair spiked without assistance, but the front worked out pretty well.
..I keep giving tips on this so often, I need to actually work with it again and take a picture. XD
Ohayocon 2011 - Rider Con!
Shoudai Tokunaga (DGP) - 0%
Deneb (Den-O) - 0%
Ankh (OOO) - 5%
Hiro Kikuchi (Clone Baby) - 10%
Hopper!Yaguruma (Kabuto) - 25%
Ryuunosuke Ikenami (Shinkenger) - 25%
Tsukasa Kadoya (Decade) - 50%
Kazari (OOO) - 80%
Ryoutarou Nogami (Den-O) - 100%
Ura!Ryoutarou Nogami (Den-O) - 100%
Shoutarou Hidari (W) - 100%