Posted here:
http://forums.qj.net/f-psp-hacks-9/t-guide-running-15-any-other-firmware-from-the-ms-using-pandora-119207.html


Originally Posted by Mathieulh:
To do what you want to achieve is very easy.

- Install the pandora firmware to the memory stick using the normal procedure. 

- Copy the files created on the memory stick somewhere on your computer

- save your flash1 registry folder into your memory stick root

- Extract 1.50 from a psar using psardumper.
extract it as encrypted and then once more as decrypted (save both dumps)

- Copy the encrypted dump folders to the root of the MS, and get pspbtcnf.txt pspbtcnf_game.txt and pspbtcnf_updater.txt from the decrypted dump, and use those to replace the ones from the encrypted dump located at ms0:/kd/

- Get the flashemu.prx and lfatfs_patched.prx from the pandora MS files you saved earlier (they are in the kd folder) and copy those into ms0:/kd/

- open ms0:/kd/pspbtcnf.txt and ms0:/kd/pspbtcnf_game.txt and ms0:/kd/pspbtcnf_updater.txt files using a text editor and :

- change /kd/lfatfs.prx to /kd/lfatfs_patched.prx

- add /kd/flashemu.prx right after the /kd/fatmsmod.prx line.

- save the files

Done, the 1.50 firmware will boot straight from the MS using the Pandora battery. Of course you may adapt this mod to another firmware such as M33.