Barb and I have done this one a couple of times although its for a whole turkey but I don't see why it wouldn't work for a turkey breast. Also go up on the Weber website and click on recipes and then click on poultry they have a few marinated Turkey breast recipes, the buttermilk one looks interesting.
Here's the one that we do.
http://www.weber.com/recipes/poultry/brined-and-barbecued-turkey-with-pan-gravy