The only way to do this sort of search would be to leverage the SNOMED CT reference maps. If you find all the descendents of the SNOMED code 74732009, and then look to see which CIEL concepts are mapped to those codes (either SNOMED CT or SNOMED NP) then you will have the subset in CIEL. Kaiser Permanente had a list of 1200 or so mental health diagnoses which are published as Convergent Medical Terminology subset.