OP, I just got back into hacking my Vita - from what I can tell (and anybody please chime in if I'm incorrect - still trying to educate myself on the last 6 months worth of hacks), but there's still ZERO way to play PS1 games on the Vita. You can use ARK I hear people say but there's no audio - that's a deal breaker.
RetroArch will freeze your PS1 game whenever the Vita goes into sleep mode – which since the Vita is a portable device that is going to happen all the time (otherwise we would be playing PS1 games on our home systems) – so that is likewise a deal breaker.
Adrenaline (unless I screwed up my most recent update I did today), likewise STILL can't play PS1 games.
Last, if you can't activate anymore (as I just read in this thread), unless your Vita is already activated you're kinda out of luck on all of the above anyway.
I still have to research if I can actually purchase PS1 games from the PS Store (which I already own physical copies on disc...), then still transfer them to my Vita via a PS3 console. - that's the only possible way to properly play PS1 games on your Vita I can think of (which I don't even know if the Vita needs to be activated to do that either...still researching like I said).