A little touchy to get a precise cutoff, so warming it up enough to suck it into a syringe and injecting to precise weights in the jar sitting on the scale, is probably the easiest.
If your going to be doing this a lot and want max efficiency and ease id recommend an auto pippete system. Epindorph has a great line of them. To speed things up You will have to become accustomed to measures by volume instead of weight.
This of course is the expensive way to go but imo the only way if you spend a lot of your day weighing and filling jars one by one