Preheat the oven to 350 degrees.
Combine rum and dried fruit in a bowl. Cover it with plastic wrap, and microwave until rum boils, 45 seconds to a minute. Set aside to cool.
Whisk the dry ingredients (flour, sugar, baking powder, salt, and all spice) in a bowl. Set aside.
Strain the dried fruit, reserving 3 tablespoons of the rum.
Whisk together the eggs, vegetable oil, vanilla extract, and the reserved rum in a mixing bowl.
Stir the rum-egg mixture with the dry ingredients. Add walnuts (or macadamia nuts), dried fruit, and coconut into the bowl. Fold them into the dough.
Using a ruler and a pencil, draw two 2 by 12-inch rectangular shapes on a parchment paper. They should be 3-4 inches apart from one another. Flip it, and place it on a baking sheet.
Divide the dough into two equal pieces and form each log into a 2X12-inch log.
Bake for 30-35 minutes, or until lightly browned. Take it out of the oven and let it cool for 15 minutes. Do not turn the oven off.
Transfer one of the logs onto a cutting board, and using a serrated knife, cut on bias into 3/4-inch-thick slices. Place the biscotti slices cut side down onto the baking sheet. Repeat the same process with the second log.
Bake for 10 minutes, flipping them halfway through the baking process.
Let cool for 20 minutes before serving.