Brew Coconut Memories tea (or your chosen flavor) as directed. Then make the cake as directed on the box, substituting brewed tea for plain water.
Alternative: Use 1 cup of coconut milk and steep the tea directly in the milk. Pour the milk through a strainer to remove the loose tea, then use one cup of the tea-infused milk and 1/4 cup water in place of milk in your cake recipe. (Can use milk by itself if you want it richer.)
Simple Tea-infused White Cake from https://www.adventureswithtea.com/simple-tea-infused-white-cake/