F ound this online:
Yes, you heard right, a new keyboard driver is out for the PSP! Coded
by harleyg and Fanjita, it is a very useful application that allows you
to use pretty much any keyboard or similar input device as a native method of input. What plugins does **** have?
-[IR] Infrared keyboard support
-[SIO] Serial I/O support via PSP headphone jack
-[CTRL] PSP button emulation (the ability to play PSP games from the keyboard instead of the PSPs regular buttons)
-[OSK] Support for detecting when PSP on-screen keyboard is active, and
the ability to interpret key presses on the keyboard to the correct
button presses on the PSP.
**** comes with an installer. The installer will ask you if you wish
to copy the **** prx to flash0 and if you want it to auto run in 1.50
game mode. Writing to flash0 may brick your PSP if something goes
wrong. BE SURE TO READ THE README AND user_guide.html LOCATED IN THE DOCS FOLDER IF YOU DON\'T WANT TO HAVE AN EXPENSIVE BRICK!
Thanks Fanjita and harleyg, and we look forward to the next release of this awesome homebrew!
So I guess you should download the zipfile and check the user guide.
Hope this helps