Here’s a little puff piece on spruce beer, in Alaska. It delves into a little history—dealing with sailors and scurvy—and even contains a recipe (I’m thinking it’s a pretty old recipe):
Boil 10 gallons (45.5 liters) of water, six pounds (2.7 kilograms) of molasses, and three ounces (85 grams) of ginger for three hours; add two pounds (.9 kilograms) of spruce tips for five minutes in the boil. Strain, add milk yeast, wait two days for fermentation.
I’ve always wanted to brew a spruce beer. I’ve used spruce essence before (in a porter, I think), but I can’t say as it added much to the beer since I was in a stage of adding everything but the kitchen sink and all the flavors tended to drown each other out.
I’d probably still use spruce essence in place of actual spruce shoots, just because they’re harder to come by (even living in the wooded Pacific Northwest). You gotta love the convenience factor of stopping at the homebrew shop and picking up little bottles of flavoring/essences/syrups for whatever you need, be it spruce or fruit syrups or what have you, rather than having to gather up the real thing…
Doing a Google search for "spruce beer" turns up a wealth of information, including many recipes. That’s a good start for learning more.