ClearCase VC (CC-VC)
An extension of the GNU Emacs VC package which understands the ClearCase configuration management system. This package is not officially supported, but the author is willing to fix bugs in it as time permits. Emacs ClearCase integration
This is a ClearCase integration package for GNU Emacs (implemented as a vc.el backend) that works with recent versions of it (including CVS version). EmacsWiki: Clear Case
Discussion and information about ClearCase tools for Emacs. Clearcase VC for NT Emacs
Extension to the Emacs lisp version control package, not just for NT.