Choose lilikoi that are wrinkled. If you choose pretty, smooth lilikoi fruits, they are young and are not sweet or rich enough to generate the rich flavor and scent you are looking for. If you must buy smooth lilikoi, allow them to ripen on the counter until their skin becomes wrinkly. Cut the lililoi in half with a sharp knife. It may help to pierce the fruit's skin with the point of the knife before slicing in half. Pull the pulp, juice and seeds out with a spoon and pour the juice, seeds and all, into the vodka. Allow it to steep for at least a month to generate the full richness the fruits are capable of. Strain the liquid though a screen or a cheesecloth to remove pulp and seeds, then pour the strained liquid into a large container. Add sugar a small amount at a time, stir until dissolved, taste; then continue to add sugar and stir until the desired sweetness is achieved.