Once you have done this successfully, any time you format a memory stick it will add a folder called 'ISO' to the root directory of the memory stick. Or, if you don't want to format, you can simply create one from your computer (while connected to it, of course), but make sure it's all caps (ISO, not iso)...
You then drop any games that have the extension .iso or .cso into this folder, go to the game section of your system (disconnected from the computer), scroll down to the memory stick instead of the UMD icon, and press X. You will then see a list of the games you have available for play off the memory stick. You may experience problems with game play, but this is usually caused by settings that need to be changed in the firmware, which you can easily do... Just look up the hacked firmware you have installed and they usually tell you how to access the settings menu for that firmware, and you'll just have to experiment with settings until you get the games to work properly.