This tutorial will show you how to install Adrenaline through VitaShell, make Adrenaline download a hacked PSP firmware so you can use it to play your backups, fix a known bug on Adrenaline, and where to put your PSP and PS1 backups.
Adrenaline mimics the official Sony PSP emulator on the Vita, it will boot up as if you are playing the PSP on 6.61 custom firmware.