taiHEN plugin for swapping X and O buttons on PSVita
Put "buttonswap.suprx" in 'tai' folder in the root of your Vita.
Change config.txt in that directory to load plugin for title of your choice by adding new lines like below:
# titleid for your game (this one is for Root//Letter for example)
*PCSB01019
ux0:tai/buttonswap.suprx
After that just run the game and your buttons should be swapped (this would work only for this game).