Jell-O shots are always fun, especially with coffee liqueur included!
Stir coffee and coffee liqueur together in a small bowl. Sprinkle evenly with 1 pack of the gelatin and let stand until fully bloomed, about 1 minute. Pour 1/2 cup of the hot water over mixture, and whisk for a minute until the gelatin has dissolved. Pour 1 ounce (2 tablespoons) of your coffee mixture into 8 shot-sized plastic cups. Refrigerate them until they set, about 30 minutes.
Combine Irish cream liqueur and pecan liqueur (if you're using it; if not, just use equal amounts of Irish cream liqueur) in a small bowl. Sprinkle with another packet of the gelatin, again letting it stand until it's bloomed, about 1 minute. Pour a 1/2 cup of the hot water over the mixture, and whisk until gelatin is dissolved, about another minute. Pour 1 ounce (2 tablespoons) Irish cream mixture on top of the gelatinized coffee layer. Refrigerate until set once again, another 30 minutes.
Pour Irish whiskey into a small bowl. Sprinkle with the last gelatin packet. You can probably guess where this is going. Let it stand until bloomed, about 1 minute. Pour remaining 3/4 cup hot water over whiskey, and whisk until gelatin dissolves, about 1 minute. Pour 1 ounce (2 tablespoons) whiskey mixture over gelatinized Irish cream layer. Refrigerate one last time until set, 45 minutes to 4 hours.