I'd be more inclined to try citrus oil than pine oil for this type of application. Sure, a lot of the pine aroma compounds are similar to what are found in hops. What I'd be worried about are some of the other tar/pitch type compounds.
I like your idea of adding it to late primary. This gives the yeast a chance to potentially metabolize some of the compounds to add some complexity.
Let us know how it turns out if you try it. I have some pure compounds that I've been meaning to try this with myself (linalool, geraniol, alpha- and beta-pinene, citronellol, etc).