Pine or spruce flavorings are semi common still to this day. For example, several years ago Anchor’s holiday ale had spruce essence in it. So it is entirely possible. I don’t know if I would personally use pine or spruce for the sole flavoring in a beer. The danger is if you use too much it gives the beer a terpetiney pine sol like flavor and tastes medicinal. The way I would go about doing this is either buy a spruce essence and add a small amount to the secondary fermentor. Then taste it when you bottle. If it’s not strong enough with the spruce add a little more to your taste. Then you can get it about where you want it. This is the safe way to do it. Because if you add to much spruce at the beginning there’s no way to take it back out. If you want to use fresh pine or spruce call and ask for Griz and he’ll explain it to you. By the way if you happen to use too much spruce and it doesn’t taste good it can be used as a “pecker disinfectant.” 
Very stimulating. Any further questions don’t hesitate to either call at 415 751 9338/800 513 5196 or email us.
Cheers!
Griz
