firmware 3.40

Hi a friend has a psp firmware 3.40 can it be hacked downgraded then custom firmware

Yea, you can either use the Pandora's Battery and Magic Memory Stick method by:
buying them
open up your battery and mess with the insides to make one
make a pandora's battery by using a psp with 1.50 or 1.50 kernel on it.
All ya need to make the memory stick is put certain files on it.

Or you can use the Lumines I downgrade by upgrading to 3.50 and then using the game Lumines I: Puzzle Fusion I think.. and put certain files on your memory stick to downgrade it to 1.50.

Once you downgrade it to 1.50 you can upgrade to a custom firmware from there.

is there a tutorial if yes is the idiots guide version cos i am slow at first

A tutorial of upgrading to custom firmware?
Or one of downgrading?