Hi and Congrats on your 1st post, aubie.
There are any number of cake recipes that are made with liquor/liqueur, fruitcake and rum cake being two that immediately came to my mind.
Here's a doctored cake mix recipe that has variations using liquor/liqueur:
However, infusing a cake with liquor is a different process than merely substituting liquor or liqueur for part of the liquid.
To infuse a cake with liquor (after it is baked) you can use a simple syrup (adding the liquor as part of the initial recipe, or making a more concentrated recipe and adding the liquor after - so that it still contains alcohol).
Everything you ever wanted to know about simple syrups...
(When and how to apply syrup, i.e., brush, spray.)
How to Apply Syrup:
Cool Syrup Applied to Cooled Cake:
Cool Syrup Applied to Hot Cake:
How Simple Syrups Add Moisture:
How CC members use simple syrup, opinions: