Its a bit tricky. I looked at it on the Steam version for reference, and didn't get much help since it was a script that injects itself into the assembly code.
I tried to make cheats for all 4 characters but the pointers for everyone except for Ajna just do not stick. In fact, Im pretty sure the cheat ZiT posted for the 2nd character only works up until you have more than two characters than it stops working. (or at least thats what happened to me)
If you look at the cheats you might notice that Ajna's HP cheat isn't nearly as complex and it's because the teammates are stored in a completely different location. My suspicion is that this is because Ajna's HP needs to be present in both the stage, and during the combat phase (The same for enemies which is also why it was easy for me to make a 1 hit kill cheat). This is because you can attack enemies, and enemies can attack you outside of combat.
Since teammates are not present outside of combat their HP is stored in a more complex way (because the game doesn't need to keep it active all the time, it just needs to bring it up when it needs it.)
Im not sure it's going to happen, I know I am no longer looking for them personally. That game is a bit of a pain since almost everything is in float, and the game is so heavily scripted. It's probably possible, but it would be MUCH easier for somebody with experience writing assembly cheats than for me to find it.
On the plus side, having Inf. HP on Ajna, Inf. Special, and enemies that die instantly MOST of the game is a breeze.