Build over ice in lowball, pour into mixing glass and back to combine. Serve on rocks.
Any balanced London dry will work. Fresh juice is especially important in this drink.
On 12/29/10, having received a bottle of Douglas fir eau de vie for Christmas, I had no idea how to mix with it. Then I remembered that Harold McGee in On Food and Cooking described the terpenes in grapefruit being similar to those of evergreens.