A more conventional method (though no more effective, I am sure

) taken from CarCareSpecialists.com. Good luck!
Cleaning White Wax Residue Stains on Trim: One of the more common problems is white wax residue stains on your exterior rubber or vinyl trim. To remove these stains, simply dampen a small spot of a clean, soft cloth with a wax solvent such as One Grand Tar, Gum & Wax Remover or undiluted Wurth Citrus Degreaser. I use a piece of 100% cotton terry cloth because the texture of the cloth helps remove the wax residue from the millions of tiny depressions in the pebble surface. Either spray a small amount on the cloth or place the cloth over the top of the bottle, hold it in place with your index finger and momentarily invert the bottle to dampen a small spot on the cloth. Rub the white stained area carefully with the solvent saturated section of the cloth to dissolve the wax residue. Repeat as necessary, as it may take several applications of solvent to remove significant amounts of wax residue. If the cloth does not get down into the bottom of these tiny depressions, then you may have to resort to a soft brush. Dampen the stained area with the solvent and gently brush the residue with a soft brush to dig out the remaining residue. Use the brush carefully, as it may scratch you paint. Once you have removed all traces of the residue, wash the trim and surrounding areas thoroughly with car wash. Rinse the area completely with water to remove any traces of solvent and then dry. Finally, apply a protective coating of your favorite rubber protectant and you are done.
To help minimize wax residue stains on your rubber trim, apply a coating of rubber protectant before you wax. This coating will help prevent the wax from adhering to the rubber or vinyl trim and any that does sneak onto the trim may usually be removed with the application of a little more rubber protectant.