an Original or Slim battery (reported not working with newer PSPs);
a >256MB and <4GB memory stick.
I. Pandora Stick + Battery
Backup your memory stick contents and format using the PSP format utility;
Connect the PSP to the PC using USB;
Unzip pandora.zip and drag the mspformat.exe and msinst.exe to C:\ (or equivalent);
Run cmd.exe, go to C:\ (type cd c\), and run mspformat.exe <memory stick drive letter> (ex: mspformat.exe D);
IMPORTANT: Remove the memory stick from the PSP first, and then, disconnect the PSP USB Connection;
Insert memory stick and plug the PSP to the PC again;
Unzip ospbt_0.52.zip, go to the memory stick (it should be empty), create PSP folder and, inside, GAME folder (PSP/GAME) and drag the ospbt_052 folder to PSP/GAME folder;
Unrar despertar_cementerio4.rar and drag the despertar_cementerio to PSP/GAME folder;
Unzip/unrar the three firmware archives, rename each one, respectively, 150.PBP, 340.PBP and 380.PBP, and drag the three to the memory stick root;
Disconnect the PSP from the PC;
Run Despertar del Cementerio, press X (the cross button) and wait for it to finish;
Connect the PSP to the PC;
If everything was done correctly until now, you should have the file msipl.bin in the root of the memory stick;
Go to cmd.exe, or if you closed it, run it again;
Run "msinst.exe <PSP drive letter> <PSP drive letter>\msipl.bin" ( ex: "msinst.exe D D:\msipl.bin" );
IMPORTANT: Like before, remove the memory stick from the PSP first, and then, disconnect the PSP USB Connection;
The Pandora Stick is ready, now for the Pandora Battery (you should use an Original PSP battery, if possible, not the Slim Battery, as it's certifiably safer)
Run OS Pandora Battery Tool 0.52, press X and select Backup battery eeprom to ms0:/eeprom.bin (this backups your battery's serial code, so you can convert the battery back to normal, if needed) and press X to continue;
After the backup, select Convert to service mode (aka: Pandora's battery) and press X to continue;
If everything went smoothly, congratulations, you have the Pandora Stick + Battery and Despertar del Cementerio v4 installed and ready to use.
II. Using Despertar del Cementerio
If you need to unbrick a bricked PSP or install custom firmware into a "virgin" PSP:
Remove the Pandora Stick + Battery from the PSP and insert first the memory stick and then the battery into the bricked PSP;
The PSP will boot automatically if the Pandora Battery was properly done;
On the screen will show up the Despertar del Cementerio menu;
Select X (cross) to install 3.80 M33 (Custom Firmware) or press O (circle) to install the Original Sony Firmware 3.80 (to ready the PSP to send to Sony Support if it's a complete brick and needs serious repair). Also, do not touch the other options as they can damage your PSP;
Wait for it to finish, press X to shutdown the PSP;
Done, the bricked/virgin PSP has now M33's custom firmware 3.80 and it's ready to use.
III. Dark-Alex's TimeMachine
The TimeMachine is used to boot the PSP to other firmwares without installing them to the PSP's flash. The main use of this is enabling the boot to 1.5 on the PSP Slim, making it possible to run old homebrew on it.
Insert the Pandora Stick into the PSP, plug the charging cable into the PSP, connect the PSP, and only then, insert the Pandora Battery;
Connect the PSP to the PC;
Unrar timemachine_0.1.rar and drag the TIMEMACHINE folder to PSP/GAME;
Disconnect the PSP and run Time Machine;
Select Install iplloader on PSP MS boot sector and then Convert Pandora/DC1-DC4 ipl into TM format;
On the PSP Slim, you can select Install 1.50 with 3.40 hw modules and Install 3.60 M33;
On the Original PSP, you can select the above, Install 1.50 and Install 3.40 OE;
Select Exit and turn your PSP off;
You have TimeMachine installed!
Now, to boot into 1.5 on the Original PSP, press /\ (triangle button) and connect your PSP; to boot into 1.50 with 3.40 hw modules on the Original or Slim PSP, press O (circle) and connect the PSP; to boot into 3.40 OE on the Original PSP press X (cross) and connect the PSP; to boot into 3.60 M33 on the Slim PSP press [ ] (square button) and connect the PSP. To use Despertar del Cementerio with TimeMachine installed, press Digital Up (the Up button) and connect the PSP. Finally, if you want to boot into the installed firmware on the PSP, just don't press any button and the PSP will boot normally.
IMPORTANT
If you're going to use TimeMachine and Pandora kit, and have more than one memory stick, you're going to have to turn every memory stick you need into Pandora Stick and install TimeMachine on them.