Just open the cheat table in moonlight engine and attach it to main.exe after you press play (need to be kinda fast).
Once you get in the game freeze all addresses in the ct and change value to 1. Make a room and put a password on it. I believe this will not work if you are not alone in the room.
I've ran into a couple of problems where in Trial Forest and in Trial Tower some of the monsters will not die no matter how many times you hit them. If you don't wanna run into this problem i suggest just doing the higher level missions. If you need to do Trial Forest and Tower and run into that problem just unfreeze all values and kill and then freeze them back.
If you run into any other problems either pm me or post here and I'll try my best to help with it.
Edit: Updated for new patch on 7/10/08 :)
The CT is already in the moonlight folder but I added it separate for those who already had