u cn actually dwngrade the 3.80 to 1.50 and then upgrade to 3.90 m33-2 using the custom firmware..
or u cn just upgrade from 1.50 to 3.80 m33 then network update to 3.90.. and u cn play those games..
if its a slim psp then u need pandora battery and magic mem stick.. u cn either try hacking the battery via soldering a wire or just buy a ready made pandora battery from your local store or online..
if u need other info etc
PSP Hacks · Hacks, PSP Downloads, Cracks, Mods, Homebrew, Utilities · Hack Sony PlayStation Portable the best.. they are also on irc for furthur assistance ;]