quester, apart from searching Oracle.com and emailing you what I find, I don't think we can help you any further.
So, let's recap:
1). Julian offered you information regarding doing a Datawarehouse ILT training course through Oracle Education. This can of course be used to "Major" in you Oracle Masters Certification
b). ehaskins has also said a PURE datawarehousing strand doesn't exist.
Is there a Pure Datawarehousing Certification? - NO!
Can you combine Datawarehousing as part of your Oracle Masters? - YES!
You have to be an Oracle 9i OCP before you can become an OCM. You have to choose 2 ILT course to "major" in prior to sitting your OCM.
All this informaion is available for you to persue at the LINK provide by Skid. We have all been very helpful. Surely, this answers your questions?