If you go to psp-hacks.com, they have the Decrypter and the Update to 5.50 Gen B-2.
I cannot post a link cause it is blocked here at my school (I am a 6th Grade Teacher :lol )
Anyways, it is right on the first page. I used the 5.50 Gen B-2 Update right on their front page. I didn't have to mess with Official Sony FW or anything, they have it all set up for you.
All you have to do it drag and drop the 3 different Update Folders to your GAME folder on your PSP, all of the files are right there within the folders. Then you update them in order and you are running Gen B 2.
It was very very very simple. I see people wondering where to put the Official FW File and stuff, the files on psp-hacks.com were all set up for you.
They also have the Decrypter. The Decrypter is what Decrypts the Eboot.bin file in the ISO's so they will play on 5.50 Gen B -2 (someone asked what it was).
Just go to psp-hacks, it was the easiest I found to upgrade. YOU DO NEED Custom Firmware 3.30 or higher to update this way, but I assume most of you are running CFW M33 anyways.