I am working on a HIPAA cloud project and am implementing a Key Store as a central repository for all of the key pairs for PHI(Private Health Information) encryption... I am not
I don't think you can. Internal endpoints are on a closed network branch, so https would normally be redundant (although I understand your compliance issues). I found this answer (to my question) very useful in figuring out the security of internal endpoints: How secure are Windows Azure internal endpoints? - see the more detailed post that Brent links to.