I'm sure there's a better way to do this, but this is how I did it. I used an eyelash comb, q-tips, Manic Panic in Atomic Turquoise, and plastic wrap.
First, I laid down a piece of plastic to protect the surface since Manic Panic does stain. I used the lash comb to get the tangles out.
Then, using the q-tips, I slathered dye on one side, flattening the extension out as I went.
Then, when that side was done, I flipped the whole thing over and did the other one.
Then I wrapped it up to let it sit. I didn't time it because Manic Panic can be literally left on overnight if you want, even on your own head. I just left it in for a few hours.
Then, I unwrapped it and rinsed it. I wanted it to be straight, but I was too lazy to get out my flat iron and it was still wet, so instead I laid it flat between some wax paper and did this:
Yep. Just plunked a bunch of shit on top of it. >.<
Later that evening it was dry, straight, and a gorgeous glossy blue!