Try using Oliver's Thunderstorm, it gets a Nice on every enemy it hits and it isn't so strong that it kills them.
For as far as 'Scroll of Truth' items go this was a good idea. Equip your weakest wand and gear. Once in a battle hit SQUARE to make everyone defend. Change everyone tactics to Do Nothing if not already. Then use Oliver's Thunderstorm repeatedly but do not kill it. If a Golden Glim drops before it gets low try and switch to Swaine to get it and steal the scroll. If not, then try mugshot and finish it off. Got all 5 within an hour and that seems to be pretty good based on stories I've heard from others.
I played around with this today. I have yet to actually get a gold glim using it. It's either from random defend or, what seems most frequent, is right after he casts love-struck. I got 3 scrolls in about 30 minutes but only one was a gold glim steal and it was in spite of all my failed Thunderstorm efforts. I can get 3-4 of them off before he's in danger of dying.