I believe S codes are HCPCS codes which are billed the same as CPT codes. That is what I was stating. Your questions are very vague so it is difficult to answer. When you say "how to bill S-codes to Medicare for denial" I'm not sure what you are asking. If you have the appropriate S code it would be billed in an 837 format. Medicare requires electronic billing unless you applied for a waiver. The 837 format is the electronic version of the CMS 1500 and the S code would go where the cpt code goes.
If you are asking for help finding the appropriate S codes then we would be unable to help based solely on your question as we don't know what service was provided to pick the appropriate S code.