make pandora with other PSP.
use pandora to put other PSP to custom firmware.
done.

use a despertar del cementerio-type 'magic memory stick' and it'll go straight to 5.00 M33-3.

tutorial here » http://forums.noobz.eu/downgrader-suppor...gress-x/0/

and lord have mercy on you if you attempted to put CXMB into the Flash0.
it goes in ms0:\SEPLUGINS (where ms0:\ is the memory stick)
and the cxmb folder goes in the root of the memory stick (ms0:\)
it tells you in the readme. and i know for a fact CXMB works on GEN.

you're seriously overcomplicating things.