Unless you wait till the beer is completely done, filter or stabilize and keg and keep cold you won't keep any of the sweetness from the lemonade concentrate (which is basically just lemon juice, lemon oil, sugar, and some stabilizers).
it's going to be quite tart and the yeast may have a hard time with the low pH but it might be good. alternately you could make a normal hefe with the lemon drop hops and then mix it will lemonade in the glass for a radler type beverage as goschman mentions.