I've had success with the following methods. I use continuous brew technique, and I add all of these to the individual bottles for secondary fermentation. I rack off the primary fermenter, add the ginger, and let them sit at warm room temp for 3 days before the fridge:
1. 2 tablespoons of sliced/peeled fresh ginger per quart of booch.
2. Trader joes makes a ginger syrup. I use about 1 tablespoon/quart.
3. I make a simple syrup out of 2 cups water and 2 cups sugar. Melt them together. Them, I add about a pound of sliced/peeled ginger and a couple tablespoons of black peppercorns. Let them sit overnight, strain out the ginger/pepper, and store in the fridge. This makes a HOT ginger tea.