Ah-hah! Got it!
Ok, so I didn't get the GAME150 to come up on the plugin loader, but it works just as fine for the purpose of recovering the corrupt save file.
And this thing worked like gangbusters.
The instructions seem simple enough AFTER you've done it, but the first time through leaves a little guesswork.
1) Correct the directory paths in the .readme.
It says to put in ms0: / Freecheat/fc_3xx.prx . What you should do is:
ms0:/FreeCheat/fc_3xx.prx
without the spaces.
2) When swapping the corrupt data and new data on steps 4,7,8, & 10 (from the instructions on the link provided by Geek9), don't just create a copy of the save file. Actually remove the data from the stick. Sometimes when you save in different save slots, the folder name changes.
Ex: FF Dissidia
If you save in slot one, the name is ULUS10437GameData00. If you save in slot two, it becomes ULUS10437GameData01. If you're not creating new data in that SAME spot, it's going to have trouble patching. So when it says backup or move back to the card, replace the file in question.
PROtip: Create a seperate backup of your save data anyways.
I managed to get confused at one point and ended up putting the wrong file in the wrong spot and the wrong time....long story short, I ended up replacing my Dissidia file with 188 hrs. of playtime and 98% completion.

BUT, I did learn from the mistake and managed to recover the data in slot two, so my g/f's play data is working just fine now! Guess I can just make a copy of hers, change the player name, and rebuild from there. Oh well, fun game anyways.

Back to the main point - I wouldn't have been screwed if I'd just kept another copy of my original data. Live and learn.
I hope this helps clarify things. If anyone needs help on this, I'd be glad to try to help. Either PM or send me an email, and I'll see what I can do. There's prolly a lot of people on here who get this, but I'd like to help out since you guys provided the info to do this!