UPDATE NOTE: IDPS stealer was patched at 3.70 firmware for PS3. So if you didn't get your IDPS before, you can't use ps3Xport.. but if you already have your IDPS this method should still work on new OFW 4.70..
UPDATE...About OFW 4.70, it seems Sony didn't patch our backup plan. So yeah, PSP ISO loading still works on OFW 4.70, even if you don't know your IDPS. Sky will update the tutorials later...
The first video shows how to obtain some necessary information, while the second one covers ISO conversion and installation.
Obtaining the IDPS, user number and HDD backup:
Similar processes exist to run (compatible) PS3 and PSX games on OFW PS3, but not from discs rips, so obtaining the backup itself could be considered piracy, I guess. As for PSP, any UMD rip should be possible to install following the next tutorials
Converting and installing a PSP game for an OFW PS3:
Tools used in these videos:
Credits: to SkyBladeCloud for the guides above..
KaKaRoTo, for ps3Xport
flatz, for the IDPS stealer
Aldo and co., for the PSP2PS3 conversion suite
the dark programmer, for the ps3Xport GUI