This is a tutorial for installing 3.52 M33 which is kinda like 3.52 OE CFW (custom firmware) , this firmware is made by Team M33 (a big thanks to them) instead of Dark alex , though the firmwares are pretty much similar .
3.52 M33-4 installation guide :
For installing this you need a 1.5 firmware psp or a psp with an older version of custom firmware - M33 or OE it doesn't matter.This cannot be installed on a PSP slim . To make your psp to 1.5 see this guide
NOTE: FOLLOW THESE STEPS CAREFULLY AND EVERYTHING WILL BE OK.
1) Format your psp (make sure you back up your files first) go to system settings and choose format memorystick and connect it to your PC . Formatting is not compulsory but recommended. Make sure your battery is 100% full
2) Download the 3.52 M33 easy installation (compiled by me) from here
3) Open it with WinRAR if you don’t have WinRar download it from here
4) So open with Winrar and copy the PSP folder to the root of your memorystick, If it asks you whether it can over write click on “YES”
5) IF you have a custom firmware psp make sure you have 1.5 kernel see tutorial here (recommended) OR just change the ''GAME'' folder to ''GAME150''
6) Disconnect the psp from the PC , scroll to the game menu > memory stick and :
i) If you have a 1.5 firmware psp click on ''KXploit Patcher'' icon if you have custom firmware psp skip this step. After you patched your 1.5 firmware psp follow step ii)
ii) click on ''3.52 M33 Creator'' icon and wait , it will take like 2 mins.
7) After it creates Press ''X'' to exit it will go back to the PSP's XMB. Then click on the ''3.52 M33 update'' icon (battery has to be full) press ''X'' to install and wait... when its done press ''X'' to exit and turn on the psp after a min.
8) You will be welcomed with the psp ''blue screen of death'' press circle and reboot your psp apply you personal settings like time and all... Congrats you now have a 3.52 M33 but wait now for the update.
1) Format your PSP . ( recommended)
2) download the update from here.
3) Copy the psp folder to the root of the psp
4) scroll to the game menu and click on the icon that has 3:33:33 written on it .
5) press X to patch and you done . Read on :
Its Recommended that you read the 3.52 M33 users guide , FAQ from here