Combine limes and juice with vinegar in the container of a blender. Blend until lime is cut into smaller pieces. Add cucumber and blend until the level in the blender measures 4 cups. Combine cucumber mixture in a large pot with salt and pectin. Bring to a boil and add the sugar all at once. Return to a boil and boil hard for 2 minutes. Seal in sterilized jars and process 10 minutes in boiling water.