Particularly interested in the Hound Dog/Don't be Cruel/ Any way you want be session.
Those particular session tapes are lost. That goes for quite some 50s stuff but not all. Check out the official collector's label "Follow that dream" for the classic albums plus sessions. Those are fantastic releases mostly. On that label you also get other stuff like live recordings, books etc.
http://www.elvis.com/news/ftd_releases.aspxPlus keep an eye out for Mike Eder's upcoming book (see thread). I'm sure you'll find some basic infos in there.