Updating psp firmware

[The Mole]

I have managed to downgrade my psp to version 1.50 but want to put some custom firmware on so i can play my retail games alongside the homebrew.

What i want to know is how i go about installing the custom firmware i have downloaded.

I need to know whatthe file should be names and where to put it on my psp in order to be able to run the update on my psp.

[EvilBoris]

I used this guide, ironically which is hosted by a moderator on the official playstation forums.

http://boardsus.playstation.com/playstation/board/message?board.id=psp&thread.id=2810436

[The Mole]

Thanks mate just what i wanted.

I get the the extracting and packing 3.10 stage and it does not go any further. The file thats created is file size 0 is that right?