For extracting flavors from nuts, I would try the vodka method on a small batch, at least. Crush up the pecans to give greater surface area. I have heard of folks extracting flavors from herbs (mint, etc) using the vodka method. It all depends on if the flavor compounds you want are alcohol soluble or oil soluble. If they're oil soluble, the only way you're likely to get them is to buy an extract to simulate the flavor.
What a great idea though. I don't even plan on pecanning mead, but I might put some pecan bits in vodka just to make a cooking extract for desserts, especially since we have the holiday tradition of "large bowl of mixed nuts that no one eats" sitting on the table right now. I might start two batches. One with pecans, one with walnuts. Nothing else in there really has a distinctive flavor.
Wait, are those hazelnuts?