It is very important to iron in a couple layers of CH4X wax to harden the base for the very cold abrasive conditons. A ski with the least amount of structure is highly recommended.
For the final wax layer, drip on CH4X and LF4X. then sprinkle on LF3 Cold powder. Iron the mixture, scrape after cooling, then brush out.
Note: You must use a very hot iron (150C or 320F) to properly melt and iron in CH4X. It takes more passes (7-10) of the iron to heat up the ski base and melt in the very hard CH4X wax. There should be about 1-2" of molten wax trailing the back edge of your iron.