I'd like to do it...
I've googled but found nothing really usefull.

You'll need to use a very very light colour, and you'll need to do it more than once.

If your hair is already dark, you'll need to go ginger for about a week, before doing it again.

If you mean that sort of ash-blonde colour, then your best bet is going to a hairdresser. I knew a guy that tried to do it and his hair turned as yellow as a pikachu.

there's no way to 'dye' your hair white, it needs bleach and toner.
Depending on how dark your hair is naturally you're gonna need to bleach it 2 or three times. Then once you've got it to a light yellowy blonde colour get some violet toner on it for about 20 mins, just make sure you keep checking on it and get rid as soon as your hair looks grey/lilac..otherwise you can end up with silver/light blue hair if left too long.
btw, if your hair is dyed already then you're gonna need to let it grow or fade out before doing this, it'll take more time with bleachings and you'll end up with dead hair thatll fall out as soon as you try do anything with it.
And between bleaches/toner you're gonna need to use a shitload of conditioner on it, bleach isn't the kindest to hair!

I know a chick who already has blonde hair but still has to bleach it around five times to get it white, and even then it still isn't white white.

It's a hard task, but it's possible. Do exactly what hopscotch said, she's got it covered. For bleach I recommend Manic Panic Flash Lightening Kit. They have a 30 volume and 40 volume you can get (40 being strongest so get that).

http://www.teachersource.com/Images/Product/md/sm10.jpg

try cutting a little bundle of hair off and see how long it takes for you to get it to the color you want

This wont be extremely acurate, seeing as different parts of the hair take way different times to bleach, like the roots vs the ends, the roots go SO quick.

http://tinyurl.com/ywycs6

That would be slick as fuck to have white hair. I'd have to gel it everyday though which might make me feel a bit metro

Metro? There's a word I haven't heard for a while.