Have you reviewed the info at this link: https://developers.thomsonreuters.com/elektron-data-solutions/datascope-select-rest-api/downloads
An alternative paradigm is to use a TREP based symbology provider so that existing API users would simply call a new RIC for conversion. Additionally one could install ATS that could then provide transparent access to the Elektron content using the alternative symbology multiverse. Such a service would still need to be sourced from DataScope Select (DSS) or Tick History (TRTH) with an "Exchange By Day" (EBD) subscription.
Note in the not too distant future Elektron clients will be able to access such a featured service through the new REFERENCE domain.