There are very few filters for CMYK. Most that exist do not work well, and are really not necessary. My suggestion to you is a simple one. Create your separations for the printer, and specify either Pantone or Spot colour inks. Use the correct inks and you'll be fine. Most service bureaus will walk you through the process if you are unsure, and at the same time will help garauntee the final outcome. Proofs can be printed most times for next to nothing.