Install custom apps on the A920?

Hello, just stumpled amoung this site http://www.hypnosoft.co.uk

There e-book publication is to show users how to install custom
software on the A920, as a kind of work around to the mesures in place
preventing people from doing so.

Does this actually work?

I'm not a technical person, so i don't want to do it, to find out it
dont work if you see what i mean.

Andy

I would like to read the book, but i'm in Australia and well i don't want to spend the money to buy that book, but i heard from someone here, that you can hack the phone and use Symbian SDK software to be able to install custom application to the phone.