I suspect the dry needles don't contain enough resins to affect the food but coniferous wood might need to be really, really dry.
Actually, I've pressed the needles to make turpentine, so they've got plenty of oils in them - more than the wood. From my experiences with campfire cooking, both the wood and the needles burn up very quickly so they add a blast of taste rather than a deep smoke flavor. Keep it uncovered and go easy on coniferous wood, though, as it creates a fair amount of soot and that's not something you want on meat.
Unless you're one of the cousins I posted about a few weeks ago. They seem to love the taste....