Place the syrup and the sugar in two separate, shallow dishes. First dip the glass rims in the syrup, then in the sugar, and leave to dry.
Toss the cherries in the sugar and place 3 cherries on each skewer.
Pour the syrup and ice cubes into the prepared glasses. Mix the Schweppes and liqueur, pour carefully into the glasses, place the skewers in the glasses and serve immediately.