Combine sugar, lime juice, water, lemon juice and orange juice in a small saucepan over medium heat. Cook, stirring, until sugar dissolves. Remove from heat and allow to cool. Once cool transfer to a blender with tequila, orange liqueur, and lime wedge and process until smooth. Pour into the cups and cover the top of each cup with foil. Place the popsicle stick in center of cup (down through foil, which will hold it in place). Freeze until hard, preferably overnight. Remove from freezer and run cup under warm water to loosen popsicle. Garnish with kosher salt and serve.