In a chilled stainless shaker, add amaretto, followed by the lemon rum. In a highball glass, fill half full with ice, and add cranberry juice. Pour the chilled mixed liquors over the ice and juice, stir once with a straw, and garnish the edge of the glass witha half orange slice. Alternatively, mix rum, amaretto, and juice in a chilled shaker and pour into a chilled martini glass with orange garnish.