They don't give it to the Zeta in game for some reason, but I quickly loaded up the game and made a cheat code to give the Zeta the psycommu trait. Add the following lines to the cheat code file "ULJS00178" in the \memstick\PSP\Cheats folder:

_C0 Zeta Psycommu
_L 0x10166A2A 0x10

Then load up the game in the emulator and go to the cheat menu, and you should have an option to enable the cheat code.