[DedSpace]

Have you personally tried this with successful results?

I doubt this. A doubling service would not be possible unless some one with a very large number of BTC was giving out theirs for free or for a small(er) fee. This is because it is impossible to create a forged entry in the blockchain. Any one with enough bitcoin to do this would be rather dumb to do so. Any one with a large number of illegitimately obtained BTC could offer people more BTC in exchange for some of their own, but it would be much easier and more profitable for them to set up a number of anonymous wallets and tumble them through those. They would then need to have their BTC in separate wallets until they were all spent or sold off so it looked like they had passed through a number of hands.

EDIT:
On a side note I actively avoid all tutorial PDFs as it is possible to put virii into them. If someone has a legitimate tutorial I would expect them to put it in a thread.