Coconut oil with soy lecithin FTW. Check out BadKittySmiles from skunkpharm!
May I suggest that Petflora'a excellent recipe be modified slightly by the addition of water to the slow cook stage, such that the water layer can be poured away after the oil and water layers have separated during the after-cook refrigeration.
The water will prevent the oil from burning during the slow cook stage, but most importantly, all the nasty weed taste dissolves in the water, and is thus removed almost entirely when the water is later poured off. I learnt of this vital water washing step from one of the sticky posts in this cooking section of the forum.