Pretty self explanatory, make villages in biomes that have BOP wood in them use the BOP wood instead of vanilla.

There really isn't an easy way to do this without copying and changing the vanilla village structure files. In past versions it was just changeable with code, as villages were all generated via code, but not anymore. Personally I'd rather not bother unless we were making unique designs for all of the villages, and I just do not have the time or desire to do that when the current villages fit in just fine.