I just put it in the juice and shake it up. It gets stuck in the funnel if you try to pour through, but if you pour some juice on top of it, it will go through with the juice and you have it where you need it to shake it up.
I agree white sugar is better, but I've liked the results in the places where I've used the brown sugar thus far. I just have to take a few extra steps to be able to manage it.