Well if it is a NON-TAv3 board yes you can use Pandora to downgrade. If not nope your stuck for now till someone finds a way. You can use homebrew using the latest HBL but no ISO loading that is for sure. There are "signed" PSP games floating around that will work just fine on your PSP as they require no mod at all as the PSP see's it as official Sony software from PSN network.
PS3 CECH-2501A [CFW] & CECH-3001 [OFW]/ PS2 SCPH-3901 & SCPH-7501/ PS1 SCPH-5501
Mod Cobra 4.46 v7.00 w/ E3 Flasher [CFW] & Cobra ODE 4.50 [OFW]/ Mod HDD-OSD [Phat] & Modbo 4.0 [Slim]/ Mod MM3
HDD 1tb [CFW] & 640gb [OFW]/ HDD 640gb & OPL v0.92 w/ 1.5tb SMB