This is what I did(I can't guarantee you that the game won't crash/freeze at chapter 5 but I played around 10 in Hall of Valhalla(this is where the game always freezed when I tried with other blue crystals codes))
1.This code is for the NTSC(USA)version of the game
2.It requires you to have enough blue crystals to restore the cheapest seal stone(or enough crystals to restore seal stone that you haven't restored yet)
3.Now for the tricky part...create a new empty 8mb card
4.Download
mymc and open the card with your save.Select it and export it.
5.Open the new card that you created and import the save that you exported
6.Select the new card that have only the VP2 save and eject the second card
7.Place the pnach file into your cheats folder,enable the cheats from System=>Enable Cheats and start the game
8.Find and restore any crystal and save to the memory card(overwrite the save)
9.Close pcsx2 and open mymc and the card on which you just saved now.
10.Export the save and import it into your old card and select the old card from pcsx2(you can't import a save into the memory card with mymc if the save already exist,so just select it and use File=>Delete and the import the save with 99999 crystals)
I played couple of battles in Hall of Valhalla and the game didn't freeze but I can't be sure because I played them on a save that I already cleared the Seraphic Gate
PS.ArtMoney won't help you here because the first line of the code is enabler...it enable the 99999 code ONLY when you restore crystals...exactly at the moment when the game is supposed to lower your crystals amount because you restore the crystal(while doing something else,this address may be assigned to something else that don't like the value that is set for 99999 crystals which can lead to crash/freeze or corrupting your save)