Hmm, I'm not really that good at laying out interfaces, but I'm tempted to agree with Ivan here and just have a Psi Attacks total at the bottom, with a couple of caveats.
Is it possible to track kills and stuns via psi: i.e. I mind control that guy, he kills two people and those are technically my kills, or I make that alien panic and he kills one of his buddies.
You could list these as Psionics in the kills list, with maybe a medal for causing an AI unit to commit suicide by grenade.
The only place I think you can afford to go into greater detail is the mission details screen, maybe listing them like PANIC Sectoid Soldier Psionics/Psi Amp
Maybe if the above is possible you could list the kills the enemy makes as a result of this in more detail too. Not entirely sure how you would present that, seeing as you'd want both the aliens weapon and the alien doing the kill on there.
Hmm, thats all I can think of at the moment, either way, having stats for psi will be interesting.