I have used elderflower in Gewurtztraminer wine in the past and it adds a nice grapefruity fragrance and taste. I used 1 oz. in a 6 gallon batch of wine.
I have also added it to Piesporter and Traminette.
for additional guidance and information on Mead and Wine. This is a great forum to learn from. Just like Homebrewtalk.com is.