I may as well post the link to my PSIV patch here:
http://www.freewebs.com/psivhellmode/updates.htm
It really is pretty hard. It's really for people that don't mind going to high levels, but in the recent updates, (in fact, yesterday,) I added some new abilities to almost all the characters, and the omitted techniques and weapons to spice it up for all players, (that's how I found this site!) The early returns I've gotten are very favorable.
I've got a few more updates in mind too. Right now, I'm tweaking the combos so that some of the neglected characters like Gryz and Demi can contribute some more. It's amazing how much hacking will actually work in this game! I just made a Firestorm combo that uses Flare instead of Foi or Flaeli, and another with St. Fire. I even had a Destruct combo that used Nasar instead of Deban to up the damage some more. I'm shocked all these changes don't crash the game!
If everyone doesn't mind, I'll post here when I update the patches... I can think of six more things I'd like to tweak as it is!