I a spruce tip APA once, and sometimes make spruce tip tea in the spring.
Spruce isn't pine, but if you do try...only add a little. Take the amount you think you should add, and add half that. My opinion (or, o-pine-nion), but if pine is like spruce - a little goes a LOOONG way.
In the APA, I added the tips at 5 minutes. One tip (so, I guess, maybe 20-30 fresh, green needles) per gallon.
Hope this helps...let us know if you go ahead with this!