Torky has today released a plugin which enables you to play 6.30 games on all popular custom firmwares.
According to the developer: " plugin also works well on the still ever-popular Firmware 5.00 M33-6, Custom Firmware Dark_Alex Creator."
• Copy the plugin into SEPLUGINS
• In game.txt add the line "ms0:/seplugins/m33_620.prx 1"
• USB into flash0/vsh/etc and edit version.txt to "release:6.20"
• In the recovery menu, make sure "use version.txt" is enabled
• Test your games on CFW