If you've time to plan, say 6 weeks, this is the Kahlua to make.
Add all the ingredients to a bowl large enough to hold them.
Mix well.
Place in a resealable container and store for at least 6 weeks.
Shake the contents to stir the contents every couple of days.
Strain Kahlua through a tea strainer of a coffee filter.
Store in pretty bottles.
Pretend you are The Dude making a beverage, man.
Coffee loves friends. Pick those flavors which you think are good chums with coffee and add them to your Kahlua.
Bay or cardamom or black pepper might be some good choices. It's your drink, so make it as personalized as you can.