lite999 on the QJ.net forums (a great forum by the way) has posted a brilliant guide teaching us exactly how to install custom firmware on any PSP (PSP 1000, 2000 & 300o) no matter what motherboard they have.
This involves using the ChickHEN .tff exploit on PSP with firmware 5.03 so if you have above that version, I’m afraid this will not work.
Without further ado, here is the guide (all credit goes to Elite999)
1 – PSP-1000, 2000, or 3000(hackable motherboard or non-hackable
motherboards).
3 – 5.03 Firmware Update (1610)
5 – Patience, yeah if you don’t have, buy some. 
1 – If you have 5.03 firmware installed, then skip this step. If you don’t have 5.03 firmware installed on the psp, then download the file supplied above and update your firmware, beware it should be 3.52m33-4 and above. Create a folder called UPDATE in PSP/GAME on your memory stick and place the eboot from the archive into the folder. Run the 5.03 Firmware update from GAME / Memory stick and you will have 5.03. The firmware required to run ChickHEN.
2 – Download the ChickHEN R2 From the download link supplied above. Open the CHickHEN R2 archive.For slim users(psp-2000,3000): place the folder inside Slim with gif images into your PSP memory stick location like so PSP/PHOTO (later it will be PSP/PHOTO/ChickHEN), for fat users(psp-1000): place the folder inside FAT with gif images into your PSP memory stick location like so PSP/PHOTO.
3 – Now place the h.bin into the root of your memory stick pro duo. Where the folders PSP, MUSIC etc are located.
4 – Go back into settings in your psp and turn off UMD Auto-Start and UMD Cache.
5 – Place the memory stick into the PSP, and navigate to your photos folder, and enter the ChickHen folder. Wait, you will see five egg giff images, these will start to load thumbnails. Your PSP may freeze and reset. Just keep retrying and ChickHEN R2 will load up….But if you see flashing colors, your PSP will reboot loading the ChickHen.
6 – Download custom firmware 5.03GEN-A for ChickHen R2 from the download link supplied above.
7 – Connect your PSP to the computer in USB Mode.
8 – Extact the 5.03GEN-A_for_HEN.zip archive for example to your desktop.
9 – Double-click on LAUNCH-ME.exe (GUI) which can be found inside the folder extracted. Now if the program didn’t launch and showed an error, then continue reading this step, if not then continue to the following step. Download .Netframework 2.0, which is the minimal version that can run “LAUNCH-ME.exe”. When the download finishes, install .NET framework.Then launch “LAUNCH-ME.exe (GUI)”. If it still displays an error, just tell me.
10 – Choose options PSP-2000 or PSP-3000 (depends of your PSP). Mode : Choose option FULL. Set driver of your psp for example: G, H, F, etc… It depends on the usb port that the psp is connected to. Click start, the files are being copied to your psp.
11 – Disconnect the PSP from USB. Navigate to the game menu, enter your memorystick, then launch the main EBOOT.PBP.
12 – When the application loads, press L or R to flash the firmware in your flash. YOU ONLY NEED MAKE IT ONE TIME!
13 – Last but not least, press () to reboot in the custom firmware.
That was a pretty easy trip wasn’t it 
.Well stay tuned for the DDC 8 tutorial, but not soon.
1 – If you shutdown the psp, the psp will not load the custom firmware again. You need to reload ChickHen R2, then launch EBOOT.PBP of GEN-A and press o when you enter the menu.
2 – Because of that, I recommend just using the standby mode.
3 – When you have installed the custom firmware in your flash, you can remove the “files” folder in the MS ROOT.For your own safety, it is better to rename or erase the prx called “flasher.prx” in the MAIN APP folder to avoid wrong flashing times.
4 – If you have a fat psp, then I recommend to install 5.00m33-6 directly using a pandora battery rather than going in all of these procedures.
5 – Don’t ever flash your psp-2000,3000(flash0)(unhacka ble motherboards). This will result in a permanent brick that can’t be fixed until a new way is found.
2 – Dark_Alex for all his great work on scene since 4 years.
3 – Miriam for his full reverse from M33 and the 5.02GEN-A.
4 – Davee for his great chickHEN R2.
5 – PSPGEN Team & Members for help and support.
5 – You for your patience and for just reading my tutorial.
Adopted from
http://blog.alltechrelated.com/2009/08/11/installing-custom-firmware-via-chickhen-on-psp-1000-2000-3000/#more-5547
For all psp lovers~!
