According to the original post, he wants to use as a mixer or as a dessert topping.
It sounds more like he wants to turn it into a liqueur, in which case he is going to have to add in a lot of syrup. He'll have to kill the yeast so that fermentation does not kick back in. For more body and smoothness, glycerin will be needed. A long time ago I was looking at what it would take to make liqueurs and was surprised about the glycerin.
Dan, here is a link that you might want to look at.
my lack of attention span is troubling.