Thinly peel the lemon (removing as little of the white path as possible) and add the whiskey. Let the zest macerate in the whiskey for at least 3 to 4 hours, reserving the rest of the lemon for some other purpose. Afterwards, remove the peel, mince 1 teaspoon and return to the whiskey, discarding the remaining pieces.
Preheat the oven to 350 degrees F. Cream the butter, both the sugars, and egg yolks together for several minutes, until the mixture is silky smooth. Pour half the whiskey with its minced peel into the pecan meal. Stir this together and beat into the cake batter until well blended. Sift together the flour and baking powder and stir into the batter. When this is well incorporated, scrape the batter into a buttered and floured 9-inch springform or bundt pan). Gently smooth the batter with a spatula and put into the preheated oven to bake for 1 hour. Then turn off the heat and leave oven door ajar, let the cake cool in the oven for 15 minutes. Remove, release the sides of the pan (or otherwise free its contents), and put the cake on a rack to cool. The cake tastes even better the next day, it does not need refrigeration and will keep in a cake tin for at least a week. Poke holes in cake on the bottom all through cake and pour remaining whiskey in, let sit for 24 hours.
Pecan meal is available in stores but you can make your own by mincing pecan bits into a fine powder. Be careful using a food processor to do this -- it is easy to end up with pecan butter instead.