How To Run Multiple ISO's Off one Stick
Ok so I figured out how to do this without any hex editing. It's not foolproof as I will explain later, but it does work and when it does it pretty easy to pull off.
Have Coded Arms working fine but want to play Dead to Rights as well? All you have to do is take the PSP_GAME folder for DTR and rename it DTR_GAME. Then replace boot.bin as usual. Then place the DTR% and DTR___1 folders in the EXISTING GAME folder. Leave the UMD_DATA.bin alone, don't try to add the DTR one, the one that came with CA works fine, I believe its a universal file.
If you've already played DTR and have a save folder on another memory stick or your computer, you can place it in the PSP/GAME/SAVEDATA folder that already exists.
So your memory stick root drive should look like this:
PSP/GAME (savedata and eboot files for loaders here)
Unfortunately, as I said earler, this isnt perfect, I can't get Lumines (no sound <32MB version) to work, it shows the logo but boots up CA instead for some reason.
I haven't tried any others but the process should be the same. So Metal Gear would be MGA_PSP, then the same steps as above. NBA would be NBA_PSP and again same steps, etc. etc. etc.
If you post this anywhere else please give me credit. Thank you.