There is 2 methods that u can do, a softmod or install a modchip, I have installed a lot of modchips which is easy if u can solder and this is the easiest method to do if you want to change your hdd as well. I haven't had much experience with softmodding but it is also a bit more difficult if you want to change your hdd, others might know more about softmodding.
I also have a disk which will configure your new hdd if you decide to install a modchip. Let me know if you need a copy of the disk
If you have any questions or want to know more just ask
Cheers
Dean