I've played around with making a ginger extract (just diced ginger root soaked on 1/2 cup vodka for a week), but I always come back to just using the fresh ginger itself.
I did a Witbier where I added 1/4 oz. of ginger to the last 5 minutes of the boil, and the ginger came across more as a "clean finisher" than an actual ginger flavor. I did an APA with 1/2 oz. that I put into the secondary, and that gave it a REAL nice ginger taste, PLUS the same clean finish.
I've never made wine, but I might swing for the fences with a full 1/2 oz. I think the higher ABV will mask some of the ginger, as well the months it will take to condition the wine. Experiment! I've only been brewing for a couple months, so what do I know?